Note: Descriptions are shown in the official language in which they were submitted.
CA 02365426 2001-12-19
METHOD AND SYSTEM FOR ENHANCED DETAIL-IN-CONTEXT VIEWING
This application claims priority from Canadian Patent Application No.
2,328,795, filed
December 19, 2000. The invention relates to the field of computer graphics
processing,
more specifically, the invention relates to the display of visual information
including
portable document format (PDF) files on a display screen of a computer.
BACKGROUND OF THE INVENTION
Display screens are the primary visual display interface to a computer. One
problem with
these visual display screens is that they are limited in size, thus presenting
a challenge to
user interface design, particularly when larger amounts of information is to
be displayed.
This problem is normally referred to as the "screen real estate problem".
Well known solutions to this problem include panning, zooming, scrolling or
combinations thereof. While these solutions are suitable for a large number of
visual
display applications, these solutions become less effective where the visual
information is
spatially related, such as maps, newspapers and such like. In this type of
information
display, panning, zooming and/or scrolling is not as effective as much of the
context of
the panned, zoomed or scrolled display is hidden.
A recent solution to this problem is the application of "detail-in-context"
presentation
techniques to the display of large surface area media, such as maps. Detail-in-
context
presentation techniques take on many forms and are useful for displaying large
amounts
of information on limited size computer screens, and are becoming more
important with
the increased use of hand held computing devices such as personal digital
assistance
(FDA's) and cell phones.
Now, in the detail-in-context discourse, differentiation is often made between
the terms
"representation" and "presentation". A representation is a formal system, or
mapping, for
specifying raw information or data that is stored in a computer or data
processing system.
For example, a digital map of a city is a representation of raw data including
street names
and the relative geographic location of streets and utilities. Such a
representation may be
1
CA 02365426 2001-12-19
displayed visually on computer screen or printed on paper. On the other hand,
a
presentation is a spatial organization of a given representation that is
appropriate for the
task at hand. Thus, a presentation of a representation organizes such things
as the point of
view and the relative emphasis of different parts or regions of the
representation. For
example, a digital map of a city may be presented with a region magnified to
reveal street
names.
Detail-in-context presentations allow for magnification of a particular region
of interest
(the "focal region") in a representation while preserving visibility of the
surrounding
representation. In other words, in detail-in-context presentations focal
regions are
presented with an increased level of detail without the removal of contextual
information
from the original representation. In general, a detail-in-context presentation
may be
considered as a distorted view (or distortion) of a portion of the original
representation
where the distortion is the result of the application of a "lens" like
distortion function to
the original representation. A detailed review of various detail-in-context
presentation
techniques may be found in a publication by Carpendale, Marianne S. T., titled
"A
Framework for Elastic Presentation Space" (Burnaby, British Columbia: Simon
Fraser
University, 1999) and incorporated herein by reference.
Thus, detail-in-context presentations of data using techniques such as Elastic
Presentation
Space ("EPS") are useful in presenting large amounts of information on limited-
size
display surfaces. Detail-in-context views allow magnification of a particular
region of
interest (the "focal region") in a data presentation while preserving
visibility of the
surrounding information. Development of increasingly powerful computing
devices has
lead to new possibilities for applications of detail-in-context viewing. At
the same time,
the development of new compact, mobile computing platforms such as handheld
computers, typically with reduced computing performance and smaller display
surfaces
as compared to desktop or mainframe computers, has motivated research into
alternate
implementation techniques and performance improvements to detail-in-context
data
presentation technologies.
2
CA 02365426 2001-12-19
Consequently, one shortcoming of current EPS graphics technology and detail-in-
context
presentation methods is that being computationally inefficient, they are not
optimized for
newer compact, mobile computing platforms (e.g. handheld computers) that have
reduced
computing power. Considerable computer processing is required to distort a
given
presentation so as to produce a detail-in-context "lens", and to move the lens
through the
data with adequate performance to provide an acceptable level of interactivity
to the user.
A need therefore exists for a method and system that will allow for the
effective
implementation of EPS graphics technology on computing platforms having
variable
levels of computing power. Consequently, it is an object of the present
invention to
obviate or mitigate at least some of the above-mentioned disadvantages.
SUMMARY OF THE INVENTION
In accordance with an aspect of the invention, there is provided an improved
method for
display of a transitional region of interest while transitioning between a
first region of
interest and a second region of interest within visual information on a
display screen of a
computer. The method comprises the steps of applying a transitional
transformation to
the visual information, the transitional transformation requiring reduced
calculations for
transforming the visual information to transitional transformed visual
information; and
displaying the transitional transformed visual information on the display
screen.
In accordance with a further aspect of the invention, there is provided a
method for
displaying the transition between regions of interest within visual
information on a
display screen of a computer. The method comprises the steps of selecting a
first region
of interest within the visual information; applying a first transformation to
the visual
information to improve the visual detail in the first region of interest; and
displaying the
first transformed visual information on the display screen. Selecting a second
region of
interest within the visual information applying a second transformation to the
visual
information to improve the visual detail in the second region of interest; and
displaying
the second transformed visual information on the display screen. Selecting a
transitional
3
CA 02365426 2001-12-19
region of interest on a path between the first region of interest and the
second region of
interest within the visual information; applying a transitional transformation
to the visual
information to improve the visual detail in a predetermined portion of the
transitional
region of interest; and displaying the transitional transformed visual
information on the
S display screen.
In accordance with yet a further aspect of the invention, there is provided a
method for
displaying visual information on a display screen of a computer. The method
comprising
the steps of selecting a region of interest within the visual information;
applying a
transformation to the visual information for improving visual detail and
presentation
quality in the region of interest, the transformation for overlaying the
visual information
on a lens surface, the lens surface having predetermined shape for the region
of interest.
Projecting the lens surface with the overlaid visual information onto a plane.
Increasing
resolution of the visual information in the region of interest. Decreasing
resolution of the
visual information outside the region of interest, and displaying the
transformed visual
information on the display screen.
In accordance with yet a further aspect of the invention, there is provided a
data carrier
having stored thereon instructions for improving display of a transitional
region while
transitioning between a first region of interest and a second region of
interest within
visual information on a display screen of a computer. The instructions
comprise the steps
of applying a transitional transformation to the visual information, the
transitional
transformation having a reduced a number of calculations required for
rendering the
transitional transformed visual information; and displaying the transitional
transformed
visual information on the display screen.
In accordance with yet a further aspect of the invention, there is provided a
method fox
displaying visual information in portable document format (P'DF) files on a
display
screen of a computer is provided. The method comprising the steps of scaling
the visual
information to produce a scaled representation to fit on the display screen,
the scaled
representation generally containing the entire content of the visual
information; selecting
4
CA 02365426 2001-12-19
a region of interest within the scaled representation; applying a
transformation to the
scaled representation to improve the visual detail in the region of interest;
and, displaying
the transformed representation on the display screen. The step of applying a
transformation furkher comprising the steps of creating a lens surface of
predetermined
shape for the region of interest; and, creating a transformed representation
by overlaying
the scaled representation on the lens surface and projecting the lens surface
with the
overlaid scaled representation onto a plane.
In accordance with yet a fiuther aspect of the invention, there is provided
the use of a
method for displaying visual information on a display screen of a computer for
displaying
visual information in portable document format (PDF) files is provided. The
method
comprising the steps of scaling the visual information to produce a scaled
representation
to fit on the display screen, the scaled representation generally containing
the entire
content of the visual information; selecting a region of interest within the
scaled
representation; applying a transformation to the scaled representation to
improve the
visual detail in the region of interest; and, displaying the transformed
representation on
the display screen.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may best be understood by referring to the following description
and
accompanying drawings which illustrate the invention. In the drawings:
FIG. 1 is a perspective view of a 3D perspective viewing fivstrum in
accordance with
known elastic presentation space graphics technology;.
FIG. 2 is a cross-sectional view of a presentation in accordance with known
elastic
presentation space graphics technology;
FIG. 3 is a block diagram of an exemplary data processing system for
implementing an
embodiment of the invention;
5
CA 02365426 2001-12-19
FIG. 4 is a screen capture of a PDF file for a newspaper page that has been
shrunk to fit a
display surface in accordance with one embodiment of the invention; and,
FIG. 5 is a flow chart illustrating a general method for displaying visual
information in
portable document format (PDF) files on a display screen of a computer in
accordance
with one embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following description, numerous specific details are set forth to
provide a thorough
understanding of the invention. However, it is understood that the invention
may be
practiced without these specific details. In other instances, well-known
software, circuits,
structures and techniques have not been described or shown in detail in order
not to
obscure the invention. The term "data processing system" is used herein to
refer to any
machine for processing data, including the computer systems and network
arrangements
described herein. The term "PDF" (Portable Document Format) is used herein to
refer to
a file format that captures all the elements of a printed document as an
electronic image
that a user can view, navigate, print, or forward to someone else. The term
"Elastic
Presentation Space" or "EPS" is used herein to refer to techniques that allow
for the
adjustment of a visual presentation without interfering with the information
content of the
representation. The adjective "elastic" is included in the term as it implies
the capability
of stretching and deformation and subsequent return to an original shape. EPS
graphics
technology is described by Carpendale in A Framework for Elastic Presentation
Space
(Carpendale, Marianne S. T., A Framework for Elastic Presentation Space
(Burnaby,
British Columbia: Simon Fraser University, 1999)) which is incorporated herein
by
reference. In EPS graphics technology, a two-dimensional visual representation
is placed
onto a surface; this surface is placed in three-dimensional space; the
surface, containing
the representation, is viewed through perspective projection; and the surface
is
manipulated to elect the reorganization of image details. The presentation
transformation
is separated into two steps: surface manipulation or distortion and
perspective projection.
In the drawings, like numerals refer to like structures or processes.
6
CA 02365426 2001-12-19
Referring to FIG. l, there is shown a perspective view 100 of a 3D perspective
viewing
frustrum 220 in accordance with known elastic presentation space ("EPS")
graphics
technology. In EPS, detail-in-context views of 2D visual representations are
created with
sight-line aligned distortions of a 2D information presentation surface within
a 3D
perspective viewing frustum 220. In EPS, magnification of regions of interest
and the
accompanying compression of the contextual region to accommodate this change
in scale
are produced by the movement of regions of the surface towards the viewpoint
240
located at the apex of the pyramidal shape 220 containing the fivstum. The
process of
projecting these transformed layouts via a perspective projection results in a
new 2D
layout which includes the zoomed and compressed regions. The use of the third
dimension and perspective distortion to provide magnification in EPS provides
a
meaningful metaphor for the process of distorting the information presentation
surface.
The 3D manipulation of the information presentation surface in such a system
is an
intermediate step in the process of creating a new 2D layout of the
information.
Referring to FIG. 2, there is shown a cross-sectional view of a presentation
200 in
accordance with known EPS graphics technology. EPS graphics technology employs
viewer-aligned perspective projections to produce detail-in-context
presentations in a
reference view plane 201 which may be viewed on a display. Undistorted 2D data
points
are located in a basal plane 210 of a 3D perspective viewing volume or frustum
224
which is defined by extreme rays 221 and 222 and the basal plane 210. A
viewpoint
("VP") 240 is located above the centre point of the basal plane 210 and
reference view
plane 201. Points in the basal plane 210 are displaced upward onto a distorted
surface 230
which is defined by a general 3D distortion function (i.e. a detail-in-context
distortion
basis fimction). The direction of the viewer-aligned perspective projection
corresponding
to the distorted surface 230 is indicated by the line FPo - FP 231 drawn from
a point FPo
232 in the basal plane 210 through the point FP 233 which corresponds to the
focus or
focal region or focal point of the distorted surface 230.
To reiterate, EPS refers to a collection of know-how and techniques .for
performing
"detail-in-context viewing" (also known as "mufti-scale viewing" and
"distortion
viewing") of information such as images, maps, and text, using a projection
technique
7
CA 02365426 2001-12-19
summarized below. EPS is applicable to multidimensional data and is well
suited to
implementation on a computer for dynamic detail-in-context display on an
electronic
display surface such as a monitor. In the case of two dimensional data, EPS is
typically
characterized by magnification of areas of an image where detail is desired,
in
combination with compression of a restricted range of areas of the remaining
information
(the "context"), the end result typically giving the appearance of a lens
having been
applied to the display surface. EPS has numerous advantages over conventional
zoom,
pan, and scroll technologies, including the capability of preserving the
visibility of
information outside the local region of interest.
In general, in EPS, the source image to be viewed is located in the basal
plane.
Magnification and compression are achieved through elevating elements of the
source
image relative to the basal plane, and then projecting the resultant distorted
surface onto
the reference view plane. EPS performs detail-in-context presentatian of n-
dimensional
data through the use of a procedure wherein the data is mapped into a region
in an (n+1)
dimensional space, manipulated through perspective projections in the (n+1)
dimensional
space, and then finally transformed back into n-dimensional space for
presentation.
For example, and referring to FIGS. l and 2, in two dimensions, EPS can be
implemented
through the projection of an image onto a reference plane 201 in the following
manner.
The source image is located on a basal plane 210, and those regions of
interest 233 of the
image for which magnification is desired are elevated so as to move them
closer to a
reference plane situated between the reference viewpoint 240 and the reference
view
plane (RVP) 201. Magnification of the "focal region" 233 closest to the RVP
varies
inversely with distance from the RVP 201. As shown in FIGS. 1 and 2,
compression of
regions outside the focal region 233 is a function of both distance from the
RVP 201, and
the gradient of the function describing the vertical distance from the RVP 201
with
respect to horizontal distance from the focal region 233. The resultant
combination of
magnification and compression of the image as seen from the reference
viewpoint 240
results in a lens-like effect similar to that of a magnifying glass applied to
the image, and
the resultant distorted image may be referred to as a "pliable display
surface". Hence, the
various functions used to vary the magnification and compression of the image
via
8
CA 02365426 2001-12-19
vertical displacement from the basal plane 210 are described as lenses, lens
types, or lens
functions. Lens fimctions that describe basic lens types with point and
circular focal
regions, as well as certain more complex lenses and advanced capabilities such
as
folding, have previously been described by Carpendale.
System. Referring to FIG. 3, there is shown a block diagram of an exemplary
data
processing system 300 for implementing an embodiment of the invention. The
data
processing system is suitable for implementing EPS technology and for viewing
PDF
files. The data processing system 300 includes an input device 310, a central
processing
unit or CPU 320, memory 330, and a display 340. The input device 310 may be a
keyboard, mouse, trackball, or similar device. The CPU 320 may include
dedicated
coprocessors and memory devices. The memory 330 may include RAM, ROM,
databases, or disk devices. And, the display 340 may include a computer screen
or
terminal device. The data processing system 300 has stored therein data
representing
sequences of instructions which when executed cause the method described
herein to be
performed. Of course, the data processing system 300 may contain additional
software
and hardware a description of which is not necessary for understanding the
invention.
Presentation of PDF Files Using EPS. According to one aspect of the invention,
EPS is
applied to the electronic and online (i.e. Internet) presentation of Portable
Document
Format ("PDF") files. PDF is a file format that captures the elements of a
printed
document as an electronic image that a user can view, navigate, print, or
forward to
someone else. PDF files are created using software products such as Adobe
AcrobatO.
To view and use a PDF file, a product such as Adobe Acrobat Reader~ is
typically used.
PDF files are especially useful for documents such as newspaper and magazine
articles,
product brochures, or flyers where it is desired to preserve the original
graphic
appearance online. For example, a PDF file may be used for the online
distribution of a
printed document where it is desirable to preserve its printed appearance.
EPS and detail-in-context viewing can be used to enhance the viewing of PDF
files. This
is affected by the electronic scaling of the document content to a size that
allows
presentation of the firll content on the display surface, with the use of
specialized EPS
9
CA 02365426 2001-12-19
lenses to enlarge regions of interest 233 to make them readable to the user.
This method
can be used to achieve the more effective presentation of PDF file content on
small
display surfaces including handheld computers. This aspect of the invention
can be
implemented with pre-placed EPS lenses on important content components
including
headlines, feature articles, tables of contents, and advertisements.
Interaction with the
reader is such that articles in the reader's region of interest 233 are
enlarged
automatically via EPS lenses of complex shape to suit the shape of the article
or other
area of interest.
Referring to FIG. 4, there is shown a scr~n capture 400 of a PDF file for a
newspaper
page that has been effectively shrunk to fit a display surface 340 according
to one
embodiment of the invention. A lens 410 has been used in the fifth column to
increase the
font size in the reader's region of interest 233. The top 420 and bottom 430
of the lens
410 are tapered to provide a continuous transition to the unmagnified text
440. Partial
overwriting of neighboring columns 450 and images 460 by the lens 410, rather
than a
lateral distortion, is performed to blend the lens 410 into the undistorted
regions 470, and
provide enough space for the lens 410 while preserving the spatial orientation
of the
neighboring columns.
The implementation of pre-placed lenses can be achieved as follows. In order
to provide
the user with an immediate view of certain regions of a file, items of
interest such as
article headlines, whole articles, or advertisements can have lenses 410 in
place when the
document is first viewed. This can be implemented, for example, through the
use of
special lens locating information (i.e. locating tags) embedded within the
source file or in
a separate data layer, indicating the characteristics, location and/or bounds
of the lens.
Method and Use. Referring to FIG. 5, there is shown a flow chart 500
illustrating a
general method for displaying visual information in portable document format
(PDF)
files on a display screen of a computer according to one embodiment of the
invention. At
step 501, the method starts. At step 502, the visual information is scaled to
produce a
scaled representation to fit on the display screen. The scaled representation
generally
CA 02365426 2001-12-19
contains the entire content of the visual information. At step 503, a region
of interest is
selected within the scaled representation. At step 504, a transformation is
applied to the
scaled representation to improve the visual detail in the region of interest.
At step 505,
the transformed representation is displayed on the display screen. At step
506, the method
S ends. Thus, elastic presentation space methodology can be used for
displaying visual
information in portable document format (PDF) files on a display screen of a
computer,.
Restricted Rendering of Lens During Lens Motion. According to another aspect
of the
invention, a restricted portion of the region of interest (i.e. the "lens")
233, for example
the border or periphery 420, 430 of a lens 410, is rendered to a display 340
during the
movement of the lens about the data space. The movement of the lens 410 may be
user
initiated or automated. By rendering only a portion of the lens 410, the
computations
required for lens movement and rendering are minimized while a presentation of
the
changing location of the lens is maintained. When movement of the lens ceases,
by user
or automated means, a full rendering of the lens in its new location can be
displayed. In
this way, the number of computations required during the movement of the lens
410 is
reduced and hence performance is improved which is especially important for
systems
300 with limited computational speed.
Blending and Selective Use of Data at Multiple Resolutions. To improve detail-
in-context
presentation quality, an increase in the spatial resolution or level of detail
within the
region of interest 233, 410 can be provided as can a smooth visual transition
from the
region of interest to surrounding regions 440, 470.
According to another aspect of the invention, an increase in resolution within
the region
of interest 233, 410 of a detail-in-context presentation is provided by the
selective high
resolution rendering to a display 340 of data within the region of interest
233, 410 and
neighbouring regions 420, 430 of a detail-in-context lens while the remaining
data 440,
470 in the presentation is rendered at low resolution. In this way, resolution
within and
about the region of interest 233, 410 can be increased with a minimum of
computing
resources (i.e. processing time and processor memory).
11
CA 02365426 2001-12-19
According to another aspect of the invention, a smooth visual transition from
the region
of interest 233, 410 to surrounding regions 440, 470 is provided by the
blending of low
and high resolution regions 410, 420, 430, 440, 470. This blending can be
accomplished
by averaging or admixing of the high and low resolution regions described
above. In this
way, a smooth visual transition can be provided from the region of interest to
surrounding
regions with a minimum of computing resources (i.e. processing time and
processor
memory).
In the case where the client device on which the data is viewed is located
apart from the
data source (e.g. connected via the Internet), it is an advantage of the
present invention
that by increasing the resolution within the region of interest and smoothing
the visual
transition from the region of interest to surrounding regions as described,
the amount of
data that has to be transferred from the data source (e.g. server) to the
viewer (e.g. client)
is minimized.
Computer Software Product. The sequences of instructions which when executed
cause
the method described herein to be performed by the exemplary data processing
system of
FIG. 3 can be contained in a computer software product according to one
embodiment of
the invention. This computer software product can be loaded into and run, by
the
exemplary data processing system of FIG. 3.
Integrated Circuit Product. The sequences of instructions which when executed
cause the
method described herein to be performed by the exemplary data processing
system of
FIG. 3 can be contained in an integrated circuit product including a
coprocessor or
memory according to one embodiment of the invention. This integrated circuit
product
can be installed in the exemplary data processing system of FIG. 3.
Although the invention has been described with reference to certain specific
embodiments, various modifications thereof will be apparent to those skilled
in the' art
without departing from the spirit and scope of the invention as outlined in
the claims
appended hereto.
12
