Note: Descriptions are shown in the official language in which they were submitted.
CA 02249976 1998-10-15
WEARABLE CAMERA SYSTEM WITH VIEWFINDER MEANS
FIELD OF THE INVENTION
The present invention pertains generally to a new photographic or video means
and
apparatus comprising a. body-worn portable electronic camera system with «-
earable
viewfinder means.
BACKGROUND OF THE INVENTION
In photography (and in movie and video production), it is desirable to capture
events in a natural manner with minimal intervention and disturbance. Current
state-of-the-art photographic or video apparatus, even in its most simple
"point and
click" form, creates a visual disturbance to others and attracts considerable
attention
on account of the gesture of bringing the camera up to the eye. Even if the
size of
the camera could be reduced to the point of being negligible (e.g. no bigger
than
the eyecup of a typical camera viewfinder, for example), the very gesture of
bringing
a device up to the eye is unnatural and attracts considerable attention,
especially
in establishments such as gambling casinos or department stores where
photography
is often prohibited. Although there exist a variety of covert cameras such a
camera
concealed beneath the jewel of a necktie clip, cameras concealed in baseball
caps,
and cameras concealed in eyeglasses, these cameras tend to produce inferior
images,
not just because of the technical limitations imposed by their small size,
but, more
importantly because they lack a means of viewing the image. Because of the
lack of a
viewfinder, investigative video and photojournalism made with such cameras
suffers
from poor composition.
It appears that apart from large view cameras upon which the image is observed
on
a ground glass, most viewfinders present an erect image. See, for example,
U.S. Pat.
No. 5095326 entitled "Keppler-type erect image viewfinder and erecting prism"
. In
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CA 02249976 1998-10-15
contrast to this fact, it is well-known that one can become accustomed,
through long-
term psychophysical adaptation (as reported by George M. Stratton, in
Psychology
Review, in 1896 and 1897) to eyeglasses that present an upside-down image.
After
wearing upside-down glasses constantly, for eight days (keeping himself
blindfolded
when removing the glasses for bathing or sleeping) Stratton found that he
could see
normally through the glasses. More recent experiments, as conducted by and
reported
by Mann, in an MIT technical report Mediated Reality, medialab vismod TR-260,
(1994), (the report is available in http://wearcam.org/mediated-
reality/index.html)
suggest that slight transformations such as rotation by a few degrees or small
image
displacements give rise to a reversed aftereffect that is more rapidly
assimilated by the
wearer, and that such effects can often have a more detrimental effect on
performing
other tasks through the camera as well as more detrimental flashbacks upon
removal of
the camera. These findings suggest that merely mounting a conventional camera
such
as a small 35mm rangefinder camera or a small video camcorder to a helmet, so
that
one can look through the viewfinder and use it it hands-free while performing
other
tasks, will result in poor performance at doing those tasks while looking
through the
camera viewfinder. Moreover, these findings suggest that doing tasks while
looking
through the viewfinder of a conventional camera, over a long period of time,
may
give rise to detrimental flashback effects that may persist even after the
camera is
removed. This is especially true when the tasks involve a great deal of hand-
eye
coordination, such as when one might, for example, wish to photograph, film,
or
make video recordings of the experience of eating or playing volleyball or the
like,
by doing the task while concentrating primarily on the eye that is looking
through
the camera viewfinder. Indeed, since known cameras were never intended to be
used
this way (to record events from a first-person-perspective while looking
through the
viewfinder) it is not surprising that performance is poor in this usage.
Part of the reason for poor performance associated with simply attaching a con-
ventional camera to a helmet is the induced parallax and the failure to
provide an
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CA 02249976 1998-10-15
orthoscopic view. Even viewfinders which correct for parallax, as described in
U.S.
Pat. No. 569222 i in which a rangefinder is coupled to a. parallax error
compensating
mechanism, only correct for parallax between the viewfinder and the camera
lens
that is taking the picture, but do not correct for parallax between the
viewfinder and
the image that would be observed with the naked eye while not looking through
the
camera.
Traditional camera viewfinders often include the ability to overlay virtual
objects,
such as camera shutter speed, or the like, on top of reality, as described in
U.S.
Pat. No. 5664244 which describes a viewfinder with additional information
display
capability.
Open-air viewfinders are often used on extremely low cost cameras, as well as
on
some professional cameras for use at night when the light levels would be too
low to
tolerate any optical loss in the viewfinder. Examples of open-air viewfinders
used on
professional cameras, in addition to regular viewfinders, include those used
on the
Grafflex press cameras of the 1940s («~hich had three different kinds of
viewfinders),
as well as those used on some twin-lens reflex cameras. While such
viewfinders, if
used with a wearable camera system, would have the advantage of not inducing
the
problems such as flashback effects described above, they would fail to provide
an
electronically mediated reality. Moreover, although such open air viewfinders
would
eliminate the parallax between what is seen in the real world and what is seen
in the
real world looking through the viewfinder, they fail to eliminate the parallax
error
between the viewfinder and the camera.
A manner of using a plurality of pictures of the same scene or object, in
which
the pictures were taken using a camera with automatic exposure control,
automatic
gain control, or the like has been proposed in 'PENCIGRAPHY' WITH AGC: JOINT
PARAMETER ESTIMATION IN BOTH DOMAIN AND RANGE OF FUNCTIONS
IN SAME ORBIT OF THE PROJECTIVE-WYChOFF GROUP, published by S.
Mann, in M.LT. (medialab vismod) tech report TR-384, December, 1994, and later
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published also in Proceedings of the IEEE International Conference on Image
Process-
ing (ICIP-96), Lausanne, Switzerland, Septerrrber 16-19, 1996, pages 193-196.
(The
report is also available on a world wide web site:
http:~~wearcam.org~icip96~index.html
as a hypertext document, along with related documents on http:~~wearcam.org.)
This
report relates to a manner of camera self-calibration in which the unknown
nonlinear
response function of the camera is determined up to a single unknown scalar
constant.
Therefore, once the camera is so understood, it rnay be used, within the
context of
the method, as a quantigraphic light measuring instrument. As each pixel of
the
camera then becomes a light measuring instrument, successive pictures in a
video
sequence become multiple estimates of the same quantity once the multiple
images
are registered and appropriately interpolated. The measurement from a
plurality of
such estimates gives rise to knowledge about the scene sufficient to render
pictures of
increased dynamic range and tonal fidelity, as well as increased spatial
resolution and
extent. In this way a rrriniature video camera as may be concealed inside a
pair of
eyeglasses may be used to generate images of very high quality, sufficient for
fine-arts
work or other uses where good image quality is needed.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a method of positioning a camera
in
which both hands rnay be left free.
It is a further object of this invention to provide a means of exposing a film
or
acquiring a picture electronically where the spatial extent (field of view) of
the image
may be ascertained without having to hold any device up to the eye.
What is described is a wearable camera and viewfinder for capturing video of
exceptionally high compositional and artistic calibre. In addition to the fact
that
covert versions of the apparatus can be used to create investigative
documentary
videos having very good composition, for everyday usage the device need not
neces-
sarily be covert. In fact, it may be manufactured as a fashionable device that
serves
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CA 02249976 1998-10-15
as both a visible crime deterrent, as well as a self-explanatory (through its
overt
obviousness) tool for documentary videomakers and photojournalists.
Another feature of the invention is that the wearable camera has a viewfinder
such
that the image may be presented in a natural manner suitable for long-term
usage
patterns.
There are several reasons why it might be desired to wear the camera over a
sustained period of time:
1. There is the notion of a personal visual diary of sorts.
2. There is the idea of being always ready. By constantly recording into a
circular
buffer, a retroactive record function, such as a button that instructs the
device
to "begin recording from five minutes ago" may be useful in personal safety
(crime reduction) as well as in ordinary everyday usage, such as capturing a
baby's first steps on video. With the prior art in photography and video, we
spend so much time preparing the camera and searching for film, batteries,
etc.,
or at the very least, just getting the camera out of its carrying case. that
we
often miss important moments like a baby's first steps, or a spontaneous
facial
expression during the opening of a gift.
3. There is the fact that the wearable camera system, after being worn for a
long period of time, begins to behave as a true extension of the wearer's mind
and body. As a result, the composition of video shot with the device is often
impeccable without even the need for conscious thought or effort on the part
of
the user. Also, one can engage in other activities, and one is able to record
the
experience without the need to be encumbered by a camera, or even the need to
remain aware, at a conscious level, of the camera's existance. This lack of
the
need for conscious thought or effort suggests a new genre of documentary video
characterized by long-term psychophysical adaptation to the device. The result
is a very natural first-person perspective documentary, whose artistic style
is
CA 02249976 1998-10-15
very much as if a recording could be made from a video tap of the optic nerve
of
the eye itself. Events that may be so recorded include involvement in
activities
such as horseback riding. climbing up a rope, or the like, that cannot
normally
be well recorded from a first-person perspective using cameras of the prior
art.
Moreover, a very natural first-person perspective genre of video results. For
example, while wearing an embodiment of the invention, it is possible to look
through the eyepiece of a telescope or microscope and record this experience,
including the approach toward the eyepiece. The experience is recorded, from
the perspective of the participant.
4. A computational system, either built into the wearable camera, or worn on
the
body elsewhere and connected to the camera system, may be used to enhance
images. This may be of value to the visually impaired. The computer may
also perform other tasks such as object recognition. Because the device is
worn
constantly, it may also function as a photographic/videographic memory aid,
e.g. to help in way-finding through the recall and display of previously
captured
imagery.
It is desired that the proposed viewfinder arrangement be suitable for long-
term
usage, such as when one may be wearing the camera for sixteen hours per day,
looking
through it all the while. Traditional viewfinders are only looked through on a
shorter
term basis. Thus there will be some important differences between the wearable
camera system and traditional cameras. For example, when the wearable camera
system comprises a zoom lens for the camera, it is desired that the viewfinder
also
comprise a zoom lens, so that when zooming into a scene, the image in the
viewfinder
can be made to subtend a lesser visual angle (appear to get smaller). It is
also desired
that the exact extent of this reduction in apparent visual angle be controlled
to exactly
cancel out the usual effect in which zooming in produces increased
magnification. In
this manner the wearable camera system provides the wearer with absolutely no
apparent magnification, or change in apparent magnification, while looking
through
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CA 02249976 1998-10-15
the viewfinder and exploring the full range of zoom adjustment.
Some viewfinders are equipped with a zoom capability. as, for example, is de-
scribed in U.S. Pat. No. 5323264, so that their field of coverage
(magnification)
varies with the varying of a zoom lens. The reader will need to be careful not
to
confuse these zoom viewfinders of the prior art with the zoom viewfinder of
the wear-
able camera invention in which viewing takes place through an electronic
viewfinder
where the decrease in visual angle subtended by the image of the viewfinder
screen is
coupled to the increase in focal length of the camera. within the proposed
invention.
This coupling negates (cancels out) any increase in magnification that would
other-
wise result from zooming in on the scene. At first this lack of increase in
apparent
magnification with increase in lens focal-length may seem counter-intuitive,
in the
sense that we normally expect zooming in to produce an increase in apparent
mag-
nification as observed while looking through a camera viewfinder. This
expectation
is owing to known cameras. However, after using the wearable camera system for
an
extended period of time, one quickly grows accustomed to the unique
characteristics
of its viewfinder, and the much more seamless integration of its viewfinder
with ev-
eryday life. This seamlessness is such that after time, the wearer will begin
to operate
the wearable camera invention without appreciable conscious thought or effort.
With
magnification, or changes in magnification, it is much more difficult to fully
adapt to
the presence of the camera.
An important aspect of the proposed invention is the capability of the
apparatus
to mediate (augment, diminish, or otherwise alter) the visual perception of
reality.
The proposed camera viewfinder is related to the displays that are used in the
field
of Virtual Reality (VR) in the sense that both are wearable. However, an
important
difference is that the proposed invention allows the wearer to continue to see
the real
world, while VR displays block out the ability to see the real world.
It is possible with the invention to allow visual reality to be mediated in
order to
make certain that exposure is correct as well as to keep the wearer of the
apparatus
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CA 02249976 1998-10-15
in the feedback loop of the photo compositional process by constantly
providing the
wearer with a video stream. Moreover, it is desired that the apparatus will
allow
the wearer to experience a computationally mediated visual reality, and for
that
experience to be shared through wireless communications networks so that the
wearer
may receive additional visual information, as well as be aware of
modifications to
visual reality that might arise, for example, as part of a communications
process in a
shared virtual environment. For such compositional and interactional
capabilities, a
simple air-based viewfinder is inadequate.
It is possible with this invention to provide such a method of exposing a film
or
acquiring a picture electronically where the tonal characteristics of the
picture may
be ascertained without having to hold any device up to the eye.
It is possible with this invention to provide such a method of exposing a film
or
acquiring a picture electronically where no apparent difference in body
movement or
gesture between when a picture is being taken and when no picture is being
taken is
detectable by others.
It is possible with this invention to provide the user with a means of
determining
the composition of the picture from a display device that is located such that
only the
user can see the display device, and so that the user can ascertain the
composition
of a picture or take a picture or video and transmit images) to one or more
remote
locations without the knowledge of others in the immediate environment.
It is possible with this invention to provide the user with a means of
determining
the composition of the picture from a display device that is located such that
only
the user can see the display device, as well as an optional additional display
device
that the user can show to others if and when the user desires to do so.
It is possible with this invention to provide the user with a means of
determining
the composition of the picture from a display device that is located such that
both
the user as well as others can see it. if the user should so desire.
It is possible with this invention to provide a wearable camera viewfinder
means in
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CA 02249976 1998-10-15
which video is displayed on a. viewfinder in such a way that all rays of light
from the
viewfinder that enter the eye appear to emanate from essentially the same
direction
as they would have had the apparatus not been worn.
It is possible with this invention to provide a means for a user to experience
additional information overlaid on top of his or her visual field of view such
that the
information is relevant to the imagery being viewed.
It is possible with this invention to provide a means and apparatus for a user
to
capture a pluralit~r of images of the same scene or objects. in a natural
process of
simply looking around, and then have these images combined together into a
single
image of increased spatial extent, spatial resolution, dynamic range, or tonal
fidelity.
It is possible with this invention to provide a viewfinder means in which the
viewfinder has a focusing mechanism that is coupled to a focusing mechanism of
a camera system. so that when the camera is focused on a particular object the
viewfinder also presents that object in a manner such that when the apparatus
moves
relative to the user's eye, the object appears to neither move with or against
the
movement of the eye, so that the rays of light entering the eye are
approximately the
same in direction as if the apparatus were not present.
It is possible with this invention to provide a viewfinder means in which the
viewfinder has a focusing mechanism that is coupled to a focusing mechanism of
a camera system, so that when the camera is focused on a particular object the
viewfinder also presents that object in the same focal depth plane as the
object
would appear to the user with the apparatus removed.
It is possible with this invention to provide a. viewfinder means in which the
viewfinder has a focusing mechanism that is controlled by an automatic
focusing
mechanism of a camera system.
It is possible with this invention to provide a stereo viewfinder means in
which
the viewfinder system has camera focusing, camera vergence, display focusing,
and
display vergence control where all four are linked together so that there is
only need
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CA 02249976 1998-10-15
for a single control.
It is possible with this invention to provide a stereo vie«-finder means in
which
the viewfinder has focusing and vergence control mechanisms that are
controlled by
an automatic focusing mechanism of a camera system.
It is possible with this invention to provide a viewfinder means in which the
viewfinder has a focusing mechanism that is controlled by an automatic
focusing
mechanism of a camera system, and in which the apparatus comprises an eye-
tracking
mechanism that causes the focus of the camera to be based on where the user is
looking, and therefore the focus of the viewfinder mechanism to be also
focused in
such a manner that the convergence of light rays from whatever object happens
to
be within the foveal region of the eye's view also produces rays of light that
have the
same focal distance as they would have had with the apparatus removed from the
user.
The proposed invention facilitates a new form of visual art, in which the
artist
may capture, with relatively little effort, a visual experience as viewed from
his or
her own perspective. With some practice, it is possible to develop a very
steady body
posture and mode of movement that best produces video of the genre pertaining
to this invention. Because the apparatus may be lightweight and close to the
head,
there is not the protrusion associated with carrying a hand-held camera. Also
because
components of the proposed invention are mounted very close to the head, in a
manner
that balances the weight distribution. Mounting close to the head minimizes
the
moment of inertia about the rotational axis of the neck, so that the head can
be
turned quickly while wearing the apparatus. This arrangement allows one to
record
the experiences of ordinary day-to-day activities from a first-person
perspective.
Moreover, because both hands are free, much better balance and posture is
possible
while using the apparatus. Anyone skilled in the arts of body movement control
as is
learned in the martial arts such as karate, as well as in dance, most notably
ballet, will
have little difficulty capturing exceptionally high quality video using the
apparatus
CA 02249976 1998-10-15
of this invention.
With known video or movie cameras, the best operators tend to be very large
peo-
ple who have trained for many years in the art of smooth control of the
cumbersome
video or motion picture film cameras used. In addition to requiring a very
large per-
son to optimally operate such cameras, various stabilization devices are often
used,
which make the apparatus even more cumbersome. The apparatus of the invention
may be optimally operated by people of any size. Even young children can
become
quite proficient in the use of the wearable camera system.
A typical embodiment of the invention comprises one or two spatial light
modula-
toys or other display means built into a pair of eyeglasses together with one
or more
sensor arrays. Typically one or more CCD (charge coupled device) image sensor
ar-
rays and appropriate optical elements comprise the camera portion of the
invention.
Typically a beamsplitter or a mirror silvered on both sides is used to combine
the
image of the viewfinder with the apparent position of the camera. The
viewfinder
is simply a means of determining the extent of coverage of the camera in a
natural
manner, and may comprise either of:
~ A reticle, graticule, rectangle, or other marking that appears to float
within a
portion of the field of view.
~ A display device that shows a video image, or some other dynamic information
perhaps related to the video image coming from the camera.
One aspect of the invention allows a photographer or videographer to wear the
apparatus continuously and therefore always end up with the ability to produce
a
picture from something that was seen a couple of minutes ago. This may be
useful to
everyone in the sense that we may not want to miss a great photo opportunity,
and
often great photo opportunities only become known to us after we have had time
to
think about something we previously sa«~.
Such an apparatus might also be of use in personal safety. Although there are
a
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growing number of video surveillance cameras installed in the environment
allegedly
for "public safety", there have been recent questions as to the true benefit
of such
centralized surveillance infrastructures. Most notably there have been several
exam-
ples in which such centralized infrastructure has been abused by the owners of
it (as
in roundups and detainment of peaceful demonstrators). Moreover. ''public
safety"
systems may fail to protect individuals against crimes committed by the
organiza-
tions that installed the systems. The apparatus of this invention allows the
storage
and retrieval of images by transmitting and recording images at one or more
remote
locations. Images may be transmitted and recorded in different countries, so
that
they would be difficult to destroy, in the event that the perpetrator of a
crime might
wish to do so.
The apparatus of the invention allows images to be captured in a natural
manner,
without giving an unusual appearance to others (such as a potential
assailant).
Moreover, as an artistic tool of personal expression, the apparatus allows the
user
to record, from a first-person-perspective, experiences that have been
difficult to so
record in the past. For example, a user might be able to record the experience
of
looking through binoculars while riding horseback, or the experience of
waterskiing,
rope climbing, or the like. Such experiences captured from a first-person
perspective
provide a new genre of video by way of a wearable camera system with
viewfinder
means that goes beyond current state-of-the-art point of view sports videos
(such as
created by cameras mounted in sports helmets which have no viewfinder means).
A typical embodiment of the invention comprises a wearable viewfinder system
which is fitted with a motorized focusing mechanism. A camera also fitted with
a
motorized focusing mechanism is positioned upon one side of a mirror that is
silvered
on both sides, so that the viewfinder can be positioned on the other side and
provide a
view that is focused to whatever the camera is focused on. Such an apparatus
allows
the user to record a portion of his or her eye's visual field of view. With
the correct
design, the device will tend to cause the wearer to want to place the
recording zone
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over top of whatever is most interesting in the scene. This tendency arises
from the
enhancement of the imagery in this zone. In much the same way that people tend
to
look at a TV set in a darkened room, regardless of what is playing (even if
the TV is
tuned to a blank station and just playing "snow" ), there is a tendency when
wearing
the invention to look at the recording/display/viewfinder zone. Therefore,
there is
a tendency to try to put the recording zone on top that which is of most
interest.
Therefore using the apparatus, after time, does not require conscious thought
or
effort. In was once said that television is more real than real life, and in
much the
same way, the wearer of the apparatus becomes a cybernetic organism (cyborg)
in
a true synergy of human and camera. This is particularly true with a low
vision
system in which one can actually see better through the viewfinder than in
real life
{e.g. at night when an image intensifier provides enhanced vision). In this
case, the
tendency of the wearer to want to become an organism that seeks best picture
is very
pronounced.
Accordingly. the present invention in one aspect comprises camera bearing head-
gear with electronic display responsive to an electronic output from the
camera so
that the electronic display may function as a viewfinder for the camera.
Preferably,
the optical arrangement of the camera and viewfinder display are such that
each ray
of light is absorbed and quantified by the camera and that the viewfinder
results in a
synthesis of the rays of light that are collinear to the rays of light
entering the cam-
era. In this way, rays of light pass through the apparatus to provide the
wearer with
an electronically mediated experience but without otherwise distorting the
spatial
arrangement, focus, or appearance of the scene viewed through the apparatus.
According to another aspect of the invention, there is provided an eyeglass
based
wearable camera system with eyeglass based viewfinder. Preferably, the optical
ar-
rangement of the camera and viewfinder display are such that each ray of light
is
absorbed and quantified by the camera and that the viewfinder results in a
synthesis
of the rays of light that are collinear to the rays of light entering the
camera. In this
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CA 02249976 1998-10-15
way, rays of light pass through the apparatus to provide the wearer with an
electron-
ically mediated experience but without otherwise distorting the spatial
arrangement,
focus, or appearance of the scene viewed through the apparatus.
According to another aspect of the invention, there is provided camera bearing
headgear with viewfinder based on a display device of a. body-worn computer
system.
Preferably, the optical arrangement of the camera and viewfinder display are
such that
each ray of light is absorbed and quantified by the camera and that the
viewfinder
results in a synthesis of the rays of light that are collinear to the rays of
light entering
the camera. In this way, rays of light pass through the apparatus to provide
the
wearer with an computer mediated experience but without otherwise distorting
the
spatial arrangement, focus, or appearance of the scene viewed through the
apparatus.
According to another aspect of the invention, there is provided a wearable
camera
system with virtual-light viewfinder, so that a portion of the light that
provides a field
of view to the wearer is diverted by converting the incoming light into a
numerical
representation, processing that numerical representation, and then taking that
pro-
cessed numerical representation and forming it back into rays of light
approximately
collinear with those rays of light that entered the apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, by way of examples which
in no way are meant to limit the scope of the invention, but, rather, these
examples
will serve to illustrate the invention with reference to the accompanying
drawings, in
which:
FIG. 1 is a diagram of a simple embodiment of the invention in which there are
two
cameras, a wide-angle camera concealed in the nose bridge of a pair of
sunglasses, a
tele-camera concealed in the top part of the frame of the sunglasses, and
combined by
way of a beamsplitter with the wide-camera, as well as a viewfinder means
concealed
in the left temple side-piece of the glasses with optics concealed in or
behind the glass
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CA 02249976 1998-10-15
of the left lens. FIG lA is an exploded view of a portion of FIG 1. FIG 1B is
a detail
view of a portion of FIG 1. FIG 1C and FIG ID illustrate aspects of the
operation
of the embodiment of FIG 1.
FIG. 2 is a diagram of the wearable camera system with an improvement in which
the viewfinder is constructed so that when other people look at the wearer of
the
apparatus they can see both of the wearer's eyes in such a way that they do
not
notice any unusual magnification of the wearer's left eye which might
otherwise look
unusual or become a problem in making normal eye contact with the wearer.
FIG. 3 illustrates the principle of a camera viewfinder which replaces a
portion
of the visual field of view with the view from a camera, yet allows the wearer
to
see through the apparatus without. experiencing anv psychophysical adaptation
or
coordinate transformation.
FIG. 4 illustrates a version of the apparatus similar to that in FIG. 1,
except
where a portion of the visual field of view is only partially replaced, owing
to the
use of polarizers to prevent video feedback, a.s well as a beamsplitter rather
than a
double-sided mirror.
FIG. 5 shows an embodiment of the invention in which there are two televisions
of difFerent sizes which are each superimposed upon exactly the field of view
that
corresponds to each of two cameras, one being wide-angle and the other being
tele.
FIG. 6 shows an embodiment of the wearable camera invention in which the
viewfinder contains considerable magnification, yet allows other people to see
both of
the wearer's eyes except for a slight amount of blocked vision which may be
concealed
by making the glasses look like bifocal glasses.
FIG. 7 shows an embodiment of the invention where there is coupling between
camera focus and viewfinder focus.
FIG. 8 shows an embodiment of the invention where there is a zoom capability,
and where the virtual light principle is preserved regardless of zoom setting.
FIG. 9 shows a stereo embodiment of the invention where both cameras are fo-
CA 02249976 1998-10-15
cused by the left camera, and where the left camera also controls the focus of
both
vie«~finders and the vergence of the entire system.
FIG. 10 shows an embodiment of the invention where an eye tracker is used to
set the stereo camera focus, the stereo viewfinder focus, and the vergence, to
all
correspond with the object. the wearer is looking at.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the invention shall now be described with reference to the preferred em-
bodiments shown in the drawings, it should be understood that the intention is
not
to limit the invention only to the particular embodiments shown but rather to
cover
all alterations, modifications and equivalent arrangements possible within the
scope
of appended claims.
In all aspects of the present invention, references to "camera" mean any
device or
collection of devices capable of simultaneously determining a quantity of
light arriving
from a plurality of directions and or at a plurality of locations, or
determining some
other attribute of light arriving from a plurality of directions and or at a
plurality
of locations. Similarly references to "display", "television", or the like,
shall not be
limited to just television monitors or traditional televisions used for the
display of
video from a camera near or distant, but shall also include computer data
display
means, computer data monitors, other video display devices, still picture
display
devices, ASCII text display devices, terminals, systems that directly scan
light onto
the retina of the eye to form the perception of an image, direct electrical
stimulation
through a device implanted into the back of the brain (as might create the
sensation
of vision in a blind person)., and the like.
With respect to both the cameras and displays, as broadly defined above, the
term
"zoom" shall be used in a broad sense to mean any lens of variable focal
length, any
apparatus of adjustable magnification, or any digital, computational, or
electronic
means of achieving a change in apparent magnification. Thus, for example, a
zoom
16
CA 02249976 1998-10-15
viewfinder, zoom television, zoom display, or the like, shall be taken to
include the
ability to display a picture upon a computer monitor in various sizes through
a process
of image interpolation as may be implemented on a body-worn computer system.
References to ''processor" , or "computer" shall include sequential
instruction, par-
allel instruction, and special purpose architectures such as digital signal
processing
hardware, Field Programmable Gate Arrays (FPGAs), programmable logic devices,
as well as analog signal processing devices.
References to "transceiver" shall include various combinations of radio
transmit-
ters and receivers. connected to a computer by way of a Terminal Node
Controller
(TNC), comprising, for example, a modem and a High Level Datalink Controller
(HDLCs), to establish a connection to the Internet, but shall not be limited
to this
form of communication. Accordingly, "transceiver" may also include analog
trans-
mission and reception of video signals on different frequencies, or hybrid
systems ,that
are partly analog and partly digital. The term "transceiver" shall not be
limited to
electromagnetic radiation in the frequence bands normally associated with
radio, and
may therefore include infrared or other optical frequencies. Moreover, the
signal need
not be electromagnetic, and "transceiver" may include gravity waves, or other
means
of establishing a communications channel.
While the architecture illustrated shows a connection from the headgear,
through
a computer, to the transceiver, it will be understood that the connection may
be
direct, bypassing the computer, if desired, and that a remote computer may be
used
by way of a video communications channel (for example a full-duplex analog
video
communications link) so that there ma.y be no need for the computer to be worn
on
the body of the user.
The term "headgear" shall include helmets, baseball caps, eyeglasses, and any
other means of affixing an object to the head, and shall also include
implants, whether
these implants be apparatus imbedded inside the skull, inserted into the back
of the
brain, or simply attached to the outside of the head by way of registration
pins
17
CA 02249976 1998-10-15
implanted into the skull. Thus "headgear'' refers to any object on, around,
upon. or
in the head, in whole or in part.
When it is said that ob j ect "A" is "borne" by object "B" , this shall
include the
possibilities that A is attached to B, that A is part of B, that A is built
into B, or
that A is B.
Fig 1 shows an embodiment of the invention built into eyeglass frames 100, typ-
ically containing two eyeglass lenses 105. An electronic wide-angle camera 110
is
typically concealed within the nose bridge of the eyeglass frames 100. In what
fol-
lows, the wide-angle camera 110 may be simply referred to as the "wide-
camera",
or as "wide-angle camera" . In this embodiment of the wearable camera, a
second
camera, 120, is also concealed in the eyeglass frames 100. This second camera
is one
which has been fitted with a lens of longer focal length, and will be referred
to as a
"narrow-angle camera", or simply a "narrow-camera" in what follows. The wide-
camera 110 faces forward looking through a beamsplitter 130. The narrow-camera
120 faces sideways looking through the beamsplitter. For clarity, the
beamsplitter
130 and camera 110 are shown separated in Fig la, while in actual
construction, the
beamsplitter is cemented between the two cameras as shown in Fig 1. The beam-
splitter 130 is typically mounted at a 45 degree angle, and the optical axes
of the two
cameras are typically at 90 degree angles to each other. The optical axes of
the two
cameras should intersect and thus share a common viewpoint. Thus the narrow
cam-
era 120 may have exactly the same field of view as the wide-camera 110.
Typically
eyeglasses with black frames are selected. and a CCD sensor array for wide-
camera
110 is concealed in a cavity which is also used as a nose bridge support, so
that the eye-
glasses have a normal appearance. Typically, the body of the wide-camera is
formed
from epoxy, which sets it permanently in good register with the beamsplitter
and the
narrow-camera 120. During setting of the epoxy, the cameras are manipulated
into
an exact position, to ensure exact collinearity of the two efFective optical
axes. The
wide-camera 110 is typically fitted with a lens having a diameter of
approximately
18
CA 02249976 1999-03-30
1/32 inch (less than one millimeter) - small enough that it cannot be easily
seen
by someone at close conversational distance to the person wearing the
eyeglasses.
The narrow-camera 120 is typically concealed in the upper portion of the
eyeglass
frames. The narrow-camera 120 is preferably custom-made, like the wide-camera,
by
encapsulating a CCD sensor array, or the like, in an epoxy housing together
with the
appropriate lens, so that cameras 110 and 120 are both bonded to beamsplitter
130,
and all three are in turn bonded to the eyeglass frame. A satisfactory narrow-
camera,
for use in small-production runs of the invention (where it is difficult to
constr uct
the housing from epoxy) is an Elmo (TM) model ~N42H camera, owing to its long
and very slender (7mm diameter) construction. In mass-production, a custom-
made
narrow-camera could be built directly into the eyeglass frames. Since the
narrow-
camera 120 is typically built into the top of the eyeglass frames, the wide-
camera
110 should also be mounted near the top of the frames, so the two optical axes
can
be made to intersect at right angles, making the effective optical axes (e.g.
that of
camera 120 as reflected in beamsplitter 130) collinear.
Preferably, a complete camera system providing NTSC video is not installed di-
rectly in the eyeglasses. Instead, wires 125 from the camera sensor arrays are
con-
cealed inside the eyeglass frames and run inside a hollow eyeglass safety
strap 126. A
satisfactory eyeglass safety strap is the safety strap that is sold under the
trademar k
"Croakies" . Eyeglass safety strap 126 typically extends to a cloth-wrapped
cable
harness 127 typically made of the same kind of hollow cloth material from
which
safety strap 126 is made. There is typically a connection between cable
harness 127
and a wiring har ness 180, where wiring harness 180 is typically not wrapped
in cloth.
Wiring harness 180 and cable harness 127 are connected together by connection
175.
Connection 175 typically includes a strain relief clip or the like that clips
to the inside
of the wearer's shirt, at the back of the neck, so that wiring harness 180
will not pull
on cable harness 127. In dais way, cable harness 127 is slack, and allows
safety strap
126 to fall slack and thus have a,u appearance that it just happened to fall
down
19
CA 02249976 1999-03-30
partially inside the wearer's shirt.
Wires 125 are run down to a belt pack or to a body-worn pack 128, often com-
prising a computer as part of processor 182, powered by battery pack 181 which
also powers the portions of the camera and display system located in the
headgear.
The processor 182, if it includes a computer, preferably contains also a
nonvolatile
storage device or network connection. Alternatively, or in addition to the
connection
to processor 182, there is often another kind of recording device, or
connection to a
transmitting device 186. The transmitter 186, if present, is typically powered
by the
same battery pack 181 that powers the processor. In some embodiments, a
minimal
amount of circuitry may be concealed in the eyeglass frames so that the wires
125
may be driven with a buffered signal in order to reduce signal loss. In or
behind
one or both of the eyeglass lenses 105, there is typically an optical system
150. This
optical system provides a magnified view of an electronic display in the
nature of a
miniature television screen 160 in which the viewing area is typically less
than one
inch (or less than 25 millimeters) on the diagonal. The electronic display
acts as a
viewfinder screen. The viewfinder screen may comprise a 1~4 inch (approx. 6mm)
television screen comprising an LCD spatial light modulator with a field-
sequenced
LED backlight. Preferably custom-built circuitry is used. However, a
satisfactory
embodiment of the invention may be constructed by having the television screen
be
driven by a coaxial cable carrying a video signal similar to an NTSC I~,S-170
signal.
In this case the coaxial cable and additional wires to power it are concealed
inside
the eyeglass safety-strap and run down to a belt pack or other body-worn
equipment
by wiring harness 180.
In some embodiments, television 160 contains a television tuner so that a
single
coaxial cable may provide both signal and power. In other embodiments the
majority
of the electronic components needed to construct the video signal are worn on
the
body, and the eyeglasses contain only a minimal amount of circuitry, perhaps
only a
spatial light modulator, LCD flat panel, or the like, with termination
resistors and
CA 02249976 1999-03-30
backlight. In this case, there are a greater number of wires 170. In some
embodiments
of the invention the television screen 160 is a VGA computer display, or
another form
of computer monitor display, connected to a computer system worn on the body
of
the wearer of the eyeglasses.
Wearable display devices have been described, such as in U.S. Pat. No.
5546099,
Head mounted display system with light blocking structure, by Jessica L. quint
and
Joel W. Robinson, Aug. 13, 1996, as well as in U.S. Pat. No. 5708449,
Binocular
Head Mounted Display System by Gregory Lee Heacock a,nd Gordon B. Kuenster,
Jan. 13, 1998. (Both of these two patents are assigned to Virtual Vision (TM),
a well-known manufacturer of head-mounted displays). A "personal liduid
crystal
image display" has been described U.S. Pat. No. 4636866, by Noboru Hattori,
Jan.
13, 1987. Any of these head-mounted displays of the prior art may be modified
into
a form such that they will function in place of television display 160.
In typical operation of the system of Fig 1, light enters the eyeglasses and
is ab-
sorbed and quantified by one or more cameras. By virtue of a connection
through
wiring harness 180, information about the light entering the eyeglasses is
available
to the body-worn computer system previously described. The computer system may
calculate the actual quantity of light, up to a single unknown scalar
constant, arriv-
ing at the glasses from each of a plurality of directions corresponding to the
location
of each pixel of the camer a with respect to the camera's center of pro
jection. This
calculation may be done using photoquantigraphic image processing. In some em-
bodiments of the invention the narrow-camera 120, is used to provide a more
dense
array of such photoquanta estimates. This increase in density toward the
center of
the visual field of view matches the characteristics of the human visual
system in
which there is a central foveal region of increased visual acuity. Video from
one or
both cameras is possibly processed by the body-worn computer 182 and recorded
or
transmitted to one or more remote locations by a body-worn video transmitter
186 or
body-worn Internet connection, such as a standard WA4DSY 56 kbps RF link with
21
CA 02249976 1999-03-30
a KISS 56 eprom running TCP/IP over an AX25 connection to the serial port of
the
body-worn computer. The possibly processed video signal is sent back up into
the
eyeglasses through wiring harness 18U a,nd appears on viewfinder screen 160,
viewed
through optical elements 150.
Typically, rather than displaying raw video on display 160, processed video is
displayed thereupon, with reference also to FIG lb (a close-up detail view of
processor
182), as follows: The video outputs from cameras 110 and 120 pass through
wiring
harness 180 into vision analysis processor 183. Vision analysis processor 183
typically
uses the output of the wide-camera. for head-tracking. This head-tracking
determines
the relative orientation (yaw, pitch, and roll) of the head based on the
visual location
of objects in the field of view of camera 110. Vision analysis processor 183
may
also perform some 3-D object recognition dr parameter estimation, or construct
a
3-D scene representation. Information processor 184 takes this visual
information,
and decides which virtual objects, if any, to insert into the viewfinder.
Graphics
synthesis processor 185 creates a computer-graphics rendering of a portion of
the 3-D
scene specified by the information processor 184, and presents this computer-
graphics
rendering by way of wires in wiring harness 180 to television screen 160.
Typically
the objects displayed are synthetic (virtual) objects overlaid in the same
position as
some of the real objects from the scene. Typically the virtual objects
displayed on
television 160 correspond to real objects within the field of view of narrow-
camera
120. In this wa,y, narrow camera 120 provides vision analysis processor 183
with extra
details about tire scene so that the analysis is more accurate in this foveal
region, while
wide-camera 110 pr ovides both an anticipatory role and a head-tr acking role.
In the
anticipatory role, vision analysis processor 183 is already making crude
estimates of
identity or parameters of objects outside the field of view of the viewfinder
screen 160,
with the possible expectation that the wearer may at any time turn his or her
head
to include some of these objects, or that some of these objects may move into
the
field of view of viewfinder 160 and narrow camera 120. With this operation,
synthetic
22
CA 02249976 1999-03-30
objects overlaid on real objects in the viewfinder provide the wearer with
enhanced
information of the real objects as compared with the view the wearer has of
these
objects outside of the viewfinder.
Thus even though television viewfinder screen 160 may only have 240 lines of
resolution, a virtual television screen, of extremely high resolution,
wrapping around
the wearer, may be implemented by virtue of the head-tracker, so that the
wearer
may view very high resolution pictures through what appears to be a small
window
that pans back and forth across the picture by the head-movements of the
wearer.
Optionally, in addition to overlaying synthetic objects on real objects to
enhance real
objects, graphics synthesis processor 182 (FIG lb) may cause the display of
other
synthetic objects on the vir tual television screen. For example, FIG lc
illustrates
a virtual television screen with some virtual (synthetic) objects such as an
Emacs
Buffer upon an xterm (text window in the commonly-used X-windows graphical
user-
interface). The graphics synthesis processor 182 causes the viewfinder screen
160
(FIG 1 ) to display a reticle seen in the viewfinder window at 192. Typically
viewfinder
screen 160 has 640 pixels across and 480 down, which is only enough resolution
to
display one xter m window since an xterm window is typically also 640 pixels
across
and 480 down (sufficient size for 24 rows of 80 characters of text). Thus the
wearer
can, by turning the head to look back and forth, position viewfinder reticle
192 on
top of any of a number of xterms 194 that appear to hover in space above
various
real objects 195. The real objects themselves, when positioned inside the
mediation
zone established by the viewfinder, may also be visually enhanced as seen
through the
viewfinder. Suppose the wearer is in a department store and, after picking up
a $7
item for purchase, the wearer approaches the casluier, hands the cashier a X20
dollar
bill, but only receives change for a $10 bill (e.g. only receives ~3 change
from X20).
Upon realizing this fact a minute or so later, the wearer locates a fresh
available,
(e.g. one that has no programs running in it so that it can accept commands)
xterm
196. The wearer makes this window active by head movement up and to the right,
23
CA 02249976 1999-03-30
as shown in Fig ld. Thus the camera functions also as a head tracker, and it
is
by orienting the head (and hence the camera) that the cursor may be
positioned.
Making a window active in the X-windows system is normally done by placing the
mouse cursor on the window and possibly clicking on it. However, having a
mouse on
a wearable camera~computer system is difficult owing to the fact that it
requires a
great deal of dexterity to position a cursor while walking around. With the
invention
described here, the viewfinder is the mouse~cursor: the wearer's head is the
mouse,
and the center of the viewfinder is the cursor. In Fig lc and Fig ld, windows
outside
the viewfinder are depicted in dashed lines, because they are not actually
visible to
the wearer. The wearer can see real objects outside the field of view of the
viewfinder
(either through the remaining eye, or because the viewfinder permits one to
see around
it). However, only xterms in the viewfinder are visible. Portions of the
xterms within
the viewfinder are shown with solid lines, as this is all that the wearer will
see.
Once the wearer selects window 196 by looking at it, then the wearer presses
the
letter "d" to begin "recor Ding", as indicated on window 196. Note that the
letter
"d" is pressed for "recorD", because the letter "r" means "Recall" (in some
ways
equivalent to "Rewind" on a traditional video cassette recorder). Letters are
typically
selected by way of a small number of belt-mounted switches that can be
operated
with one hand, in a manner similar to the manner that courtroom stenographers
use to form letters of the alphabet by pressing various combinations of
pushbutton
switches. Such devices are commonly known as "chording keyboards" and are well
known in the prior art. Also note that the wearer did not need to look right
into all
of window 196: the window accepts commands as long as it is active, and
doesn't
need to be wholly visible to accept commands.
Recording is typically retroactive, in the sense that the wearable camera
system,
by default, always records into a 5-minute circular buffer, so that pressing
"d" begins
recording starting from 5 minutes a,go, e.g. starting from 5 minutes before
"d" is
pressed. This means that if the wearer presses "d" within a couple of minutes
of
24
CA 02249976 1999-03-30
realizing that the cashier short-changed the wearer, then the transaction will
have
been sucessfully recorded. The customer can then see back into the past 5
minutes,
and can assert with confidence (through perfect photographic/videographic
memory
Recall, e.g. by pressing "r" ) to the cashier that a X20 bill was given. The
extra
degree of personal confidence afforded by the invention typically makes it
unnecessary
to actually present the video record (e.g. to a supervisor) in order to
correct the
situation. Of course, if there was a belief that the cashier was dishonest,
the customer
could file a report or notify authorities while at the same time submitting
the recording
as evidence. Typically the recording is also transmitted by way of transmitter
186 so
that the cashier or other representatives of the department store (such as a
department
store security guard who might be a close personal friend of the cashier)
cannot sieze
and destroy the storage medium upon which the recording was made.
Note that lucre the drawings depict objects moved translationally (e.g. the
group
of translations specified by two scalar parameters) while in actual practice,
virtual ob-
jects undergo a projective coordinate transformation in two dimensions,
governed by
eight scalar parameters, or objects undergo three dimensional coordinate
transforma-
tions. When the virtual objects are Ilat, such as text windows, such a user-
interface
is called a "Reality Window Ma,na,ger" (RWM).
In using the invention, typically various windows appear to hover above
various
real objects, and regardless of the orientation of the wearer's head (position
of the
viewfinder ), the system sustains the illusion that the virtual objects 194
(in this
example, xterms) are attached to real objects 198. The act of panning the head
back-and forth in order to navigate around the space of virtual objects also
may cause
an extremely high-resolution picture to be acquired through appropriate
processing
of a plurality of pictures captured on narrow-camera 120. This action mimicks
the
function of the human eye, where saccades are replaced with head movements to
sweep out the scene using the ca.mera's light-measurement ability as is
typical of
photoquantigraphic image processing. Thus head movements are used to direct
the
CA 02249976 1999-03-30
camera to scan out a scene in the same way that eyeball movements normally
orient
the eye to scan out a scene.
Processor 182 is typically responsible for ensuring that the view rendered in
graph-
ics processor 185 matches the viewing position of the eye in front of optics
150, and
not the original position from which the video was presented from cameras 110
and
120 to vision processor 183. Thus there is a change of viewing angle, in the
rendering,
so as to compensate for the difference in position (parallax) between the
cameras and
the view afforded by the display.
Some homographic and quantigr aphic image analysis embodiments do not require
a 3-D scene analysis, and instead use 2-D projective coordinate
transformations of
a flat object or flat surface of an object, in order to effect the parallax
correction
between virtual objects and the view of the scene as it would appear with the
glasses
removed from the wearer.
A drawback of the apparatus depicted in )ig 1 is that the optical elements 150
block the eyes) of the wearer. The wearer rnay be able to adapt to this
condition, or
at least compensate for it through the display of video from the wearable
camera to
create an illusion of transparency, in the same way that a hand-held camcorder
creates
an illusion of transparency when it is on and running even though it would
function
as a vision-blocking eye patch when turned off. However, because of the par
allax
between cameras 110 and 120 and the actual eye position given by viewfinder
optics
150, creating the illusion of transparency requires passing all objects
through the
analysis processor 183, followed by the synthesis processor 185, and this may
present
processor 182 with a formidable task. Moreover, the fact that the eye of the
wearer
is blocked means that others cannot make eye-contact with the wearer. In
social
situations this creates an unnatural form of interaction. Although the lenses
of the
glasses may be made sufl ciently dark that the viewfinder optics are
concealed, it is
preferable that the viewfinder optics may be concealed in eyeglasses that
allow others
to see both of the wearer's eyes. A beamsplitter may be used for this purpose,
but it
26
CA 02249976 1999-03-30
is preferable that there be a strong lens directly in front of the eye of the
wearer to
provide for a wide field of view. While a special contact lens might be worn
for this
purpose, there are limitations on how short the focal length of a contact lens
can be,
and such a solution is inconvenient for other reasons.
Accordingly, a viewfinder system is depicted in Fig 2 in which an optical path
200 brings light from a viewfinder screen 210, through a first relay mirror
220, along
a cavity inside the left temple-side piece of the glasses formed by an opaque
side
shield 230, or simply by hollowing out a temple side-shield. Light travels to
a second
relay mirror 240 and is combined with light from the outside environment as
seen
through diverging lens 250. The light from the outside and from the viewfinder
is combined by wa,y of beamsplitter 260. The rest of the eyeglass lenses 261
are
typically tinted slightly to match the beamsplitter 260 so that other people
looking
at the wearer's eyes do not see a dark patch where the beamsplitter is.
Converging
lens 270 magnifies the image froze the viewfinder screen 210, while canceling
the effect
of the diverging lens 250. The result is that others can look into the
wearer's eyes
and see both eyes at normal magnification, while at the same time, the wearer
can
see the camera viewfinder at increased magnification. The rest of the system
of Fig 2
is similar to that of Fig 1 (and like parts have been given like reference
numerals in
their last two digits), except that the video transmitter 186 shown in Fig 1
has been
replaced with a data communications transceiver 286. Transceiver 286 along
with
appropriate instructions loaded into computer 282 provides a camera system
allowing
collabor anon between the user of the apparatus and one or more other persons
at
remote locations. This collaboration may be facilitated through the
manipulation
of shared virtual objects such as cursors, or computer graphics renderings
displayed
upon the camera, viewfinders) of one or more users.
Similarly, transceiver 286, with appropriate instructions executed in computer
282,
allows multiple users of the invention, whether at remote locations or side-by-
side,
or in the same room within each other's field of view, to interact with one
another
27
CA 02249976 1999-03-30
through the collaborative capabilities of the apparatus. This also allows
multiple
users, at remote locations, to collaborate in such a way that a virtual
environment
is shared in which camera-based head-tracking of each user results in
acquisition of
video and subsequent generation of virtual information being made available to
the
other(s).
Multiple users, at the same location, may also collaborate in such a way that
multiple camera viewpoints may be shared among the users so that they can
advise
each other on matters such as composition, or so that one or more viewers at
remote
locations can advise one or n pore of the users on matters such as composition
or
camera angle.
Multiple users, at different locations, may also collaborate on an effort that
may
not pertain to photography or videography directly, but an effort nevertheless
that is
enhanced by the ability for each person to experience the viewpoint of
another.
It is also possible for one or more remote participants at conventional
deslaop
computers or the like to interact with one or more users of the camera system,
a,t
one or more other locations, to collaborate on an effort that may not pertain
to
photography or videography directly, but an effort nevertheless that is
enhanced by
the ability for one or more users of the camera system to either provide or
obtain
advice from or to another individual at a remote location.
The embodiments of the wearable camera system depicted in Fig 1 and Fig 2
give rise to a small displacement between the actual location of the camera,
and the
location of the virtual image of the viewfinder. Therefore, either the
parallax must be
corrected by a vision system 183, followed by 3-D coordinate transformation
(e.g. in
processor 184), followed by re-rendering (e.g. in processor 185), or if the
video is fed
through directly, the wearer must learn to make this compensation mentally.
When
this mental task is imposed upon the wearer, when performing tasks at close
range,
such as looking into a microscope while wearing the glasses, there is a
discrepancy
that is difficult to learn, and may also give rise to unpleasant
psychophysical effects
28
CA 02249976 1999-03-30
such as nausea or "flashbacks". Initially when wearing the glasses, the
tendency is
to put the microscope eyepiece up to one eye, rather than the camera 110 which
is right between the eyes. As a result, the apparatus fails to record exactly
the
wearer's experience, until the wearer can learn that the effective eye
position is right
in the middle. Locating the cameras elsewhere does not help appreciably, as
there
will always be some error. It is preferred that the apparatus will record
exactly the
wearer's experience. Thus if the wearer looks into a microscope, the glasses
should
recor d that experience for others to observe vicariously through the wearer's
eye.
Although the wearer can learn the difference between the camera position and
the
eye position, it is preferable that this not be required, for otherwise, as
previously
described, long-term usage ma,y lead to undesirable flashback effects.
Accordingly, Fig 3 illustrates a. system whereby rays of light spanning a
visual
angle from ray 310 to ray 320 enter the apparatus and are intercepted by a two-
sided mirror 315, typically mounted a.t a 45 degree angle with respect to the
optical
axis of a camera 330. These rays of light enter camera 330. Camera 330 may be
a
camera that is completely (only) electronic, or it may be a hybrid camera
comprising
photographic emulsion (film) together with a video tap, electronic previewer,
or other
manner of electronic oi.~tput, so that a film may be exposed and the
composition may
also be determined by monitoring an electronic output signal. Such a camera
that
provides an electronic output signal from which photographic, videographic, or
the
like, composition can be judged, will he called an "electronic camera"
regardless of
whether it may also contain other storage media such as photographic film. The
video output of the camera 330 is displayed upon television screen 340
possibly after
having been processed on a, body--worn computer system or the like. A
reflection
of television screen 340 is seen in the other side of mirror 315, so that the
television
image of ray 310 appears as virtual ray 360 and the television image of ray
320 appears
as ra,y 370. Since the camera 330 records an image that is backwards, a
backwards
image is displayed on the television screen 340. Since the television 340 is
observed
2J
CA 02249976 1999-03-30
in a mirror, the image is reversed again so that the view seen at pencil of
light rays
390 is not backwards. In this way a portion of the wearer's visual field of
view is
replaced by the exact same subject matter, in perfect spatial register with
the real
world as it would appear if the apparatus were absent. Thus the portion of the
field
of view spanned by rays 310 to 320 which emerges as virtual light, will align
with
the surrounding view that is not mediated by the apparatus, such as rays 311
and
321 which pass through the apparatus and enter directly into the eye without
being
deflected by two-sided mirror 315. The image could, in principle also be
registered in
tonal range, using the photoquantigr aphic image processing framework for
estimating
the unknown nonlinear response of the camera, and also estimating the response
of
the display, and compensating for both. So far focus has been ignored, and
infinite
depth-of-field has been assumed. In practice, a viewfinder with a focus
adjustment
is used, and the focus adjustment is driven by a servo mechanism controlled by
an
autofocus camera. 'hhus camera 330 automatically focuses on the sub ject
matter of
interest, and controls the focus of viewfinder 330 so that the apparent
distance to
the object is the same while looking through the apparatus as with the
apparatus
removed.
It is desirable that embodiments of the wearable camera system comprising
manual
focus cameras have the focus of the camera linked to the focus of the
viewfinder so that
both may be adjusted together with a single knob. Moreover, a camera with zoom
lens may be used together with a viewfinder having zoom lens. The zoom
mechanisms
are linked in such a way that the viewfinder image magnification is reduced as
the
camera magnification is increased. Through this appropriate linkage, any
increase in
magnification by the camera is negated exactly by decreasing the apparent size
of the
viewfinder image.
The calibration of the autofocus zoom camera and the zoom viewfinder may be
done by temporarily removing the mirror 315 and adj usting the focus and zoom
of
the viewfinder to maximize video feedback. This must be done for each zoom
setting,
CA 02249976 1999-03-30
so that the zoom of the viewfinder will properly track the zoom of the camera.
By
using video feedback as a calibration tool, a computer system may monitor the
video
output of the camera while adjusting the viewfinder and generating a lookup
table for
the viewfinder settings corresponding to each camera setting. In this way,
calibr ation
may be automated during manufacture of the wearable camera system.
The apparatus of Fig 3 does not permit others to make full eye-contact with
the wearer. Accordingly, Fig 4 depicts a similar apparatus in which only a
portion
of the rays of the leftmost ray of light 310 is deflected by beamsplitter 415
which
is installed in place of mirror 315. The visual angle subtended by incoming
light
ray 310 to light ray 320 is deflected by way of beamsplitter 415 into camera
330.
Output from this camera is displayed on television 340, possibly after
processing on
a body-worn computer or processing at one or more remote sites, or a
combination
of local and remote image processing or the like. A partial reflection of
television
340 is visible to the eye of the wearer by way of beamsplitter 415. The
leftmost
ray of light 460 of the partial view of television 340 is aligned with the
direct view
of the leftmost ray of light 310 from t;he original scene. Thus the wearer
sees a
superposition of whatever real object is located in front of ray 310 and the
television
picture of the same real object at the same location. The rightmost ray of
light 320 is
similarly visible through the beamsplitter 415 in register with the rightmost
virtual
ray reflected off the beamsplitter 415.
Note that the partial transparency of beamsplitter 415 allows one to see
beyond
the screen, so it is not necessary to carefully cut beamsplitter 415 to fit
exactly the
field of view defined by television 340, or to have the degree of silvering
feather out
to zero at the edges beyond the field of view defined by television 340.
Rays 460 a.nd 4 7 0 differ from rays 360 and 370 in that 460 and 470 present
the
viewer with a combination of virtual light and real light. In order to prevent
video
feedback, in which liglut from the television screen would shine into the
camera, a po-
larizes 480 is positioned in front of the camera. The polarization axis of the
polarizes
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CA 02249976 1999-03-30
is aligned at right angles to the polarization axis of the polarizes inside
the television,
assuming the television already has a built-in polarizes as is typical of
small battery
powered LCD televisions, LCD camcorder viewfinders, and LCD computer monitors.
If the television does not have a built in polarizes, a polarizes is added in
front of the
television. Thus video feedback is prevented by virtue of the two crossed
polarizers
in the path between the television 340 and the camera 330. Alternatively,
instead of
using explicit polarizers, a beamsplitter with polarization properties may be
used for
beamsplitter 415. Although many beamsplitters will exhibit some polarization
prop-
erties, on account of being somewhat near the Brewster angle (functioning
somewhat
like a Brewster plate), certain kinds of beamsplitters, such as dichroic
beamsplitters,
exhibit very strong polarization characteristics. For example, beamsplitter
415 may
comprise a dichroic beamsplitter cube.
The pencil of rays of light 490 will provide a mixture of direct light from
the scene,
and virtual light from the television display 340. The pencil of rays 490 thus
differs
from the pencil of rays 390 (FIG 3) in that 490 is a superposition of the
virtual light
as in 390 with real light from the scene.
In describing this invention, the term "pencil" of rays shall be taken to mean
rays
that intersect at a point in arbitrary dimensions (e.g. 3D as well as 2D) even
though
the term "pencil" usually only so-applies to 2D in common usage. This will
simplify
matters (rather than having to use the word "bundle" in 3D and "pencil" in
2D).
It is desired that both the real light and virtual light be in perfect or near
perfect
registration. However, in order that the viewfinder provide a distinct view of
the
world, it may be desirable that the virtual light from the television be made
different
in color or the like from the real light from the scene. For example, simply
using
a black a,nd white television, or a black and red television, or the like, or
placing a
colored filter over the television, will give rise to a unique appearance of
the region
of the wearer's visual field of view by virtue of a difference in color
between the
television image and the real world upon which it is exactly super imposed.
Even with
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CA 02249976 1999-03-30
such chromatic mediation of the television view of the world, it may still be
difficult
for the wearer to discern whether or not video is correctly exposed.
Accordingly,
a pseudocolor image ma,y be displayed, or unique patterns may be used to
indicate
areas of over exposure or under exposure. Once the wearer becomes aware of
areas
of improper exposure (such as when an automatic exposure algorithm is
failing), the
parameters of the automatic exposure algorithm (such as setting of program
mode
to "backlight", "high contrast", "sports mode" or the like) rnay be changed,
or the
automatic exposure may be overridden.
Television 340 may also be fitted with a focusing lens so that it may be
focused
to the same apparent depth as the real objects in front of the apparatus. A
single
manual focus adjustment may be used for both camera 330 and television 340 to
adjust them both together. Alternatively, an autofocus camera 330 may control
the
focus of television 340. Similarly, if a varifocal or zoom camera is used, a
varifocal
lens in front of television 340 should be used, and should be linked to the
camera
lens, so that a single l.nob may be used to adjust the zoom setting for both.
The apparatus of hig 4 may be calibrated by temporarily removing the
polarizes,
and then adjusting the focal length of the lens in front of television 340 to
maximize
video feedback for each zoom setting of camera 330. This process may be
automated
if desired, for example, using video feedback to generate a lookup table used
in the
calibration of a servo mechanism controlling the zoom and focus of television
340.
The entire apparatus is typically concealed in eyeglass frames in which the
beam-
splitter is either embedded in one or both glass lenses of the eyeglasses, or
behind one
or both lenses. In the case in which a monocular version of the apparatus is
being
used, the apparatus is built into one lens, and a dummy version of the
bearnsplitter
portion of apparatus may be positioned in the other lens for visual symmetry.
These
beamsplitters ma,y be integrated into the lenses in such a manner to have the
appear-
ance of ordinary lenses in ordinary bifocal eyeglasses. Mor eover,
magnification ma,y
be unobtrusively introduced by virtue of the bifocal characteristics of such
eyeglasses.
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CA 02249976 1999-03-30
Typically the entire eyeglass lens is tinted to match the density of the
beamsplitter
portion of the lens, so there is no visual discontinuity introduced by the
beamsplitter.
Fig 5 depicts a foveated embodiment of the invention in which incoming light
500 and 501 is intercepted from the direct visual path through the eyeglasses
and
directed instead, by double-sided mirror 510 to beamsplitter 520. A portion of
this
light passes through beamsplitter 520 and is absorbed and quantified by wide-
camera
530. A portion of this incoming light is also rehected by beamsplitter 520 and
directed
to narrow-camera 540. The image from the wide-camera 530 is displayed on a
large
screen television 550, typically of size 0.7 inches (approx. l8mm) on the
diagonal,
forming a wide-field-of-view image of virtual light 551 from the wide-camera.
The
image from the narrow-camera 540 is displayed on a small screen television
560,
typically of screen size 1~4 inch (approx. 6mm) on the diagonal, forming a
virtual
image of the narrow-camera as virtual light 561.
Real rays of light in the periphery of the mediation zone formed by the
apparatus
emerge as virtual rays from television 550 only. ror example, real ray 500
emerges as
virtual ray 551.
Real rays near the central (foveal) region of the mediation zone emerge as
virtual
rays from both televisions (e.g. they also emerge as virtual rays from
television
560). Television 560 subtends a smaller visual angle, and typically has the
same total
number of scanlines or same total number of pixels as television 550, so the
image is
sharper in the central (foveal) region. Thus television 560 is visually rrrore
dominant
in that region, and the viewer can ignore television 550 in this region (e.g.
the blurry
image and the sharp image superimposed appear as a sharp image in the central
region).
Thus, for example, unlike the real light ray 500 which emerges as virtual
light
from only one of the two televisions (from only television 550), the real
light ray 501
emerges as vir teal light from botlu televisions. Only one of the virtual rays
collinear
with real ra.y 501 is shown, in order to emphasize the fact that this virtual
ray is
34
CA 02249976 1999-03-30
primarily associated with television 560 (hence the break between where the
solid
line 501 is diverted by mirror 510 and where the collinear portion continues
after
mirror 570). This portion of the dotted line between mirror 510 and mirror 570
that
is collinear with real light ray 510 has been omitted to emphasize the visual
dominance
of television 560 over television 550 within the central (foveal) field of
view,
In this foveal region, it is the virtual light from television 560 that is of
interest, as
this virtual light will be perceived as more pronounced, since the image of
television
560 will be sharper (owing to its more closely packed pixel array or
scanlines). Thus
even though real light ray 501 emerges as two virtual rays, only one of these,
561, is
shown: the one corresponding to television 560.
A smaller television screen is typically used to display the image from the
narrow-
camera in order to negate the increased magnification that the narrow-camera
would
otherwise provide, when equal magnification lenses are used for both. In this
manner,
there is no magnification, and both images appear as if the rays of light were
passing
through the apparatus, so that the virtual light rays align with the real
light rays
were they not intercepted by the double-sided mirror 510. Television 550 is
viewed as
a reflection in mirror 510, while television 560 is viewed as a reflection in
beamsplitter
570. Note also that the distance between the two televisions 550 and 560
should equal
the distance between double-sided mirror 510 and beamsplitter 570 as measured
in a direction perpendicular to the optical axes of the cameras. In this way,
the
apparent distance to both televisions will be the same, so that the wearer
experiences
a view of the two televisions superimloosed upon one-another in the same depth
plane. Alternatively, the televisions may be equipped with lenses to adjust
their
magnifications so that the television displaying the image from the tele
camera 540
subtends a smaller visual angle than the television displaying the image from
wide
camera 530, and so that these visual angles match the visual angles of the
incoming
rays of light 500. In this way, two television screens of equal size may be
used,
which simplifies manufacture of the apparatus. Typically, the entire apparatus
is
CA 02249976 1999-03-30
built within the frames 590 of a hair of eyeglasses, where cameras 530 and
540, as
well as televisions 550 and 560 are concealed within the frames 590 of the
glasses,
while double-sided mirror 510 and beamsplitter 570 are mounted in, behind, or
in
front of the lens of the eyeglasses. In some embodiments, mirror 510 is
mounted to
the front of the eyeglass lens, while beamsplitter 570 is mounted behind the
lens.
In other embodiments, one or both of mirror 510 and beamsplitter 570 are
actually
embedded in the glass of the eyeglass lens.
Two-sided mirror 510 may instead be a beamsplitter, or may be fully silvered
in
places (to make a partial beamsplitter and partial fully silvered two-sided
mirror).
For example, it may be silvered more densely in the center, where the visual
acuity is
higher, owing to the second television screen. It may also be feathered out,
so that it
slowly fades to totally transparent around the edges, so there is not an
abrupt discon-
tinuity between the real world view and the portion that has been replaced by
virtual
light. In this case, it is often desirable to insert the appropriate
polarizer(s) to prevent
video feedback around the edges, or to use appropriate polarizing
beamsplitters, such
as dichroic beamsplitter materials.
Fig 6 depicts an alternate embodiment of the wearable camera invention
depicted
in Fig 4 in which both the ca,nrera and television are concealed within the
left temple
side-piece of the eyeglass frames. A first beamsplitter 610 intercepts a
portion of
the incoming light and directs it to a second beamsplitter 620 where some of
the
incoming light is directed to camera 630 and some is wasted illuminating the
televi-
sion screen 640. I-lowever, the screen 640, when presented with a video signal
from
camera 630 (possibly after being processed by a body-worn computer, or
remotely
by way of wireless communications, or the like) directs light back through
beam-
splitter 620, where some is wasted but is absorbed by the eyeglass frame to
ensure
concealment of the apparatus, and some is directed to beamsplitter 610. Some
of
this light is directed away from the glasses and would be visible by others,
and some
is directed to the curved mirror 650 where it is magnified and directed back
toward
36
CA 02249976 1999-03-30
beamsplitter 610. The por tion that is reflected off of beamsplitter 610 is
viewed by
the wearer, while the portion that continues back toward beamsplitter 620 must
be
blocked by a polarizes 660 to prevent video feedback. Implicit in the use of
polarizes
660 is the notion that the television produces a polarized output. This is
true of LCD
televisions which comprise a liquid crystal display between crossed polaroids.
If the
television is of a type that does not already produce a polarized output, an
additional
polarizes should be inserted in front of television 640. Finally, if it is
desired that the
apparatus be unobtrusive, an additional polarizes or polarizing beamsplitter
should
be used so that the television 640 is not visible to others by way of its
reflection in
beamsplitter 610. Beamsplitter 610 may, for example, be a dichroic cube
beamsplitter
that has polarization properties. Alternatively, in certain situations it may
actually
be desirable to make the display visible to others. For example when the
system
is used for conducting interviews, it might be desirable that the person being
inter-
viewed see himself or herself upon the screen. This may be facilitated by
exposing
beamsplitter G20 to view, or allowing the reflection of the television to be
seen in
beamsplitter 610. Alternatively, another television may be mounted to the
glasses,
facing outwards. Therefore, just as the wearer of an embodiment of the
invention
may see the image captured by the camera, along with additional information
such
as text of a teleprompter, the inter viewee(s) may also be presented with an
image of
themselves so that they appear to be looking into an electronic mirror, or may
be
teleprompted by this outward-facing display, or both. In Borne embodiments of
the
invention, the use of two separate screens was useful for facilitation of an
interview,
in which the same image was presented to both the inward-facing television and
the
outward-facing television, but the images were mixed with different text. In
this
way the wearer was teleprompted with one stream of text, while the interviewee
was
prompted with a different stream of text.
While the optical elements of tl~e camera system o~ the described embodiments
are
embedded in eyeglasses, equally these elements ma,y be embedded in other
headgear
37
CA 02249976 1999-03-30
such as a helmet.
The beamsplitter 415 of figure 4 and 610 of figure 6 could conveniently be
imple-
mented as a metallisation within a lens of the eyeglasses. These beamsplitters
and
diverging lens 250 of figure 2 may be embedded within the eyeglass lens below
the
main optical axis of the eye in its normal position so that the embedded
elements
may appear to be a feature of bifocal eyeglasses.
Fig 7 depicts a wearable camera system with automatic focus. While the system
depicted in Fig 3 may operate with a fixed focus camera 330, so long as it has
sufficient
depth of field, there is still the question of at what focus depth television
340 will
appear. Ideally the apparent depth of the display would match that of objects
seen
around the display, a,s represented by rays of light 311, 321, which are
beyond two-
sided mirror 315. This may be achieved if display medium 340 is such that it
has
nearly infinite depth of field, for example, by using a scanning laser
ophthalmoscope
(SLO), or other device which displays an image directly onto the retina of the
eye,
for display 340, or if display 340 were a holographic video display.
A lower-cost alternative is to use a variable focus display. The primary
objects)
of interest, 700 are imaged by lens assembly 710 which is electronically
focusable
by way of a servo mechanism 720 linked to camera 730 to provide automatic
focus.
Automatic focus cameras are well known in the prior art, so the details of
automatic
focus mechanisms will not be explained here. A signal, 750, from the automatic
focus camera is derived by way of reading out the position of the servo 720,
and this
signal 750 is conveyed to a display focus controller (viewfinder focus
controller) 760.
Viewfinder focus controller 760 drives, by way of focus control signal 770, a
servo
mechanism 780 which adjusts the focus of viewfinder optics 790. The
arrangement of
signals and control systems is such that the apparent depth of television
screen 340
is the same as the apparent depth at which the primary ob ject(s) of interest
in the
real scene would appear without the wearable camera apparatus.
Other objects, 7 O1, located in different depth planes, will not be in focus
in camera
38
CA 02249976 1999-03-30
730, and will thus appear blurry on screen 340. They may appear slightly
rnisaligned
with where they would have appeared in the absence of the wearable camera
system.
The degree of misalignment will depend on eye position - the misalignment may
or
may not be present, or may be quite small. However, because the objects are
out of
focus, and are not the primary details of the scene, a small possible
misalignment will
not be particularly objectionable to the wearer of the apparatus.
In this example, rays 310 and 311 are both in the depth plane of the central
object
of interest, so that there is no discontinuity between emergent virtual light
360 and
real light 311. Thus there is no discontinuity in perceived depth at the
leftmost edge
of two-sided mirror 315. There is, however, a difference in depth between
virtual ray
370 of real ray 320 and almost adjacent real ray 321, because virtual ray 370
is in the
same depth plane as 310, 311, and 360, while real ray 321 is in a more distant
depth
plane owing to the more distant facing surface of objects 701. However,
because the
eye will be focused on the depth plane of 310, 311, and 360, ray 311 from the
real
world will be out of focus by virtue of the limited depth of focus of the
human eye
itself. Thus the real objects will appear blurry, and a discontinuity between
these real
objects and their blurry image on screen 340 will not be appreciably
perceptible.
Fig 8 depicts a,n embodiment of the wearable camera system having a zoom lens.
Rays of light, for example, rays 500 and 501, enter the wearable camera system
and
emerge from display 840 as virtual light rays 800 and 801 respectively. In
this process
of going from light input to virtual light output, two-sided mirror 510 serves
to
deflect light to autofocus camera 7 30. Autofocus camera 730 comprises lens
810 and
servo mechanism 820 configured in such a manner as to function as a
conventional
automatic focus camera functions, exc<:pt that there is, provided to the rest
of the
system, a signal 750 that indicates the focus setting of the camera 730 and
its lens 810
as selected by the camera's cont=rol system and servo mechanism 820, and that
the
camera is also a zoom camera. in which the zoom setting ca,n be controlled
remotely
by zoom signal input 850. Zoom signal input 850 controls, by way of servo 820,
the
39
CA 02249976 1999-03-30
relative position of various optical elements 810, so that, in addition to
automatic
focus, the camera can be given a desired focal length (field of view). The
focus signal
750 goes into a focus and zoom controller 860 which accepts a zoom control
signal
input, 852, from the user, and directs this zoom control signal to the camera
by way
of signal 850, and also directs an appropriately processed version of this
zoom control
signal 851 to display controller 861. In this embodiment, display zoom is
achieved as
an electronic zoom. While camera zoom is achieved optically, display zoom is
achieved
electronically, by way of display controller 861 and display signal 870. The
camera
zooms in by adjustment of lens 810 for longer focal length, increasing the
focal distance
from the lens to the sensor array in camera 730, resulting in increased
magnification.
This increase in magnification is acompanied by a decrease, by operation of
display
controller 861, of the image size displayed on television 840. Television 840
may differ
from television 340 (of FIG 7) in the sense that television 840 is optimized
for display
of resampled (electronically resized) images. This reduction in image size
cancels out
what would otherwise be an increase in magnification when zooming in with
camera
730. It is this precicely controlled cancellation of any magnification that
ensures that
rays of light entering the apparatus are collinear with rays of virtual light
emerging
from the other side of the appar atus.
Fig. 9 depicts a stereo embodiment of the wearable camera system. An eyeglass
frame comprising left temple side-piece 910 and r fight temple side-piece 911
contains
two complete assemblies, 920 and 9'?l, each one similar to the entire assembly
depicted
in Fig 7 or Fig 8.
Rays of light, for example, ray 320, enter the left eye assembly 920, and
emerge as
rays of virtual light, for example, 370. As a result, a focus of autofocus
camera 730
results, by virtue of the main object of interest before assembly 920. The
autofocus
camera 730 includes a servo mechanism 720, and the control voltage that the
camera
feeds to this servo rnechanisrn to keep the camera in focus is also sent
outside assembly
920 to focus controller 930. Focus controller 930 drives camera 731 inside the
right
CA 02249976 1999-03-30
eye assembly 921. Lamer a 731 is not an autofocus camera, but, instead is a
remotely
focusable camera. By remotely focusable, what is meant is that rather than
having
its servo mechanism 721 driven by the camera itself, as it hunts for best
focus, the
servo mechanism is instead driven by an external signal. This external signal
comes
from the camera ?30 in the left eye assembly 920. The reason for not having
two
independently automatically focusing cameras is that it is desired that both
cameras
will focus in the same depth plane irrespective of slight errors that might be
present
in the focus of either one.
Focus controller 930 also sets the focus of both left and right viewfinders by
con-
trolling left viewfinder lens servo 780 and right viewfinder lens servo ?81.
Moreover,
focus controller 930 sends a signal to vergence controller 940 which drives
servo mech-
anism 950 to adjust the vergence of left eye assembly 920 and servo mechanism
951
to adjust the vergence of right eye assembly 921.
In this embodiment, the focus of both cameras, the focus of both displays, and
the vergence of both assemblies are all controlled by the focus of the left
camera, so
that whatever object the left camera focuses itself onto, will define the
depth plane
perceived by both eyes looking at their respective displays. This depth plane
will also
correspond to the vergence of the displays, so that depth and disparity will
match at
all times.
Fig. 10 depicts the left eye portion of an embodiment of the wearable camera
sys-
tem where the camera focus and vergence are driven by the output of an
eyetracker.
Eyetracker assembly 1010 (comprising camera and infrared light sources)
illuminates
and observes the eyeball by way of rays of light 1011 that partially reflect
off beam-
splitter 1020. Beamsplitter 1020 also allows the wearer to see straight
through to
mirror 315 and thus see virtual light from viewfinder 340. The eyetracker 1010
re-
ports the direction of eye gaze and conveys this information as a signal 1012
to eye
tracker processor 1030 which converts this direction into "X" and "Y"
coordinates
that correspond to the screen coordinates of viewfinder screen 340. These "X"
and
41
CA 02249976 1999-03-30
"Y" coordinates, which are expressed as signal 1031, indicate where on the
viewfinder
screen 340 the wearer is looking. Signal 1031 and the video output 1032 of
camera
730 are both passed to focus analyzer 1040. Focus analyzer 1040 selects a
portion
of the video signal 1032 in the neighbourhood around the coordinates specified
by
signal 1031. In this way, focus analyzer 1040 ignores video except in the
vicinity of
where the wearer of the apparatus is looking. Because the coordinates of the
cam-
era match the coordinates of the display (by way of the virtual light
principle), the
portion of video analyzed by focus analyzer 1040 corresponds to where the
wearer is
looking. The focus analyzer 1040 examines the high-frequency content of the
video
in the neighbourhood of where the wearer is looking, to derive an estimate of
how
well focused that portion of the picture is. This degree of focus is conveyed
by way
of focus sharpness signal 1041 to focus controller 1050 which drives, by way
of focus
signal 1051, the servo mechanism 720 of camera 730. Focus controller 1050 is
such
that it causes the servo mechanism 720 to hunt around until it sharpness
signal 1041
reaches a global or local maximum.
The focus analyzer 1040 and focus controller 1050 thus create a feedback
control
system around camera 730 so that it tends to focus on whatever objects) is
(are)
in the vicinity of camera and screen coordinates 1031. Thus camera 730 acts as
an
automatic focus camera, but instead of always focusing on whatever is in the
center of
its viewfinder, it focuses on whatever is being looked at by the left eye of
the wearer.
In addition to driving the focus of the left camera 730, focus controller 1050
also
provides a control voltage 1052 identical to the control voltage of 1051.
Control signal
1052 drives servo mechanism 780 of lens 790, so that the apparent depth of the
entire
screen 340 appears focused at the same depth as whatever object the wearer is
looking
at. In this way, all objects in the viewfinder appear in the depth plane of
the one the
wearer is looking at.
h~ocus controller 1050 provides further control voltages, 1053 and 1054 for
the right
eye camera a,nd right eye viewfinder, where these signals 1053 and 1054 are
identical
42
CA 02249976 1999-03-30
to that of 1051. Moreover, focus controller 1050 provides the same control
voltage to
the vergence controller 940 so that it can provide the control signal to angle
the left
and right assemblies inward by the correct amount, so that all focus and
vergence
controls are based on the depth of the object the left eye is looking at. It
is assumed
left and right eyes are looking at the same object, as is normal for any
properly
functioning human visual system.
In other embodiments of the invention, it may be desired to know which object
is of interest when there are multiple objects in the same direction of gaze,
as might
happen when the wearer is looking through a dirty glass window. In this case
there are
three possible objects of interest: the object beyond the window, the object
reflected
in the glass, and the dirt on the window. All three may be at different depth
planes
but in the same gaze direction.
An embodiment of the wearable camera system with a human-driven autofocus
camera (e.g. driven by eye focus), could be made from an eye tracker that
would
measure the focus of the wearer's left eye. Preferably, however, two
eyetrackers may
be used, one on the left eye, and one on the right eye, in order to attempt to
indepen-
dently track each eye, and attempt to obtain a better estimate of the desired
focus
by way of the vergence of the wearer's eyes.
A reality window manager (RWM), similar to that depicted in Fig lc and Fig ld,
may also be driven by the eyetracker, so that there can be an independent head
position (framing) and. cursor position (where looking), rather than always
having
the cursor in the center of the viewfinder. This arangement would also
facilitate
movement of the cursor without moving the head, which may reduce head
movements
that appear unnatural to others watching the user of the wearable camera
system.
The apparatus of this invention allows the wear er to experience the camera
over
a long period of time. For example, after wearing the apparatus sixteen hours
per
day for several weeks, it begins to function a,s a true extension of t;he mind
and
body. In this way, photogr aphic composition is much more optimal, because the
act
43
CA 02249976 1999-03-30
of taking pictures or shooting video no longer requires conscious thought or
effort.
Moreover, the intentionality of the picture-taking process is not evident to
others, be-
cause picture-taking is not preceeded by a gesture such as holding a
viewfinder object
up to the eye. The wearable viewfinder is an important element of the wearable
cam-
era invention allowing the wearer to experience everyday life through a
screen, and
therefore be always ready to capture anything that might happen, or even
anything
that might have happened previously by virtue of the retroactive record
capability
of the invention. Moreover, additional information beyond just exposure and
shutter
speed may be displayed in the camera viewfinder. For example, the camera
allows
the wearer to augment, diminish, or otherwise alter his or her perception of
visual
reality. This mediated-reality experience may be shared. The wearer may allow
oth-
ers to alter his or her perception of reality. In this way the invention is
useful as
a new communications medium, in the context of collaborative photography,
collab-
orative videography, and telepresence. Moreover, the invention may perform
other
useful tasks such as functioning as a personal safety device and crime
deterrent by
virtue of its ability to maintain a video diary transmitted and recorded at
multiple
remote locations. As a tool for photojournalists and reporters, the invention
has clear
advantages over other competing technologies.
From the foregoing description, it will thus be evident that the present
invention
provides a design for a wearable camera with a viewfinder. As various changes
can
be made in the above embodiments and operating methods without departing from
the spirit or scope of the invention, it is intended that all matter contained
in the
above description or shown in the accompanying drawings should be interpreted
as
illustrative and not in a limiting sense.
Variations or modifications to the design and construction of this invention,
within
the scope of the invention, may occur to those skilled in the art upon
reviewing
the disclosure herein. Such variations or modifications, if within the spirit
of this
invention, are intended to be encompassed within the scope of any claims to
patent
44
CA 02249976 1999-03-30
protection issuing upon this invention.
