An experiment is reported which tests whether network information is more effectively displayed in a three dimensional space than in a two dimensional space. The experimental task is to trace a path in a network and the experiment is carried out in 2D, in a 3D stereo view, in a 2D view with head coupled perspective, and in a 3D stereo view with head coupled perspective; this last condition creates a localized virtual reality display. The results show that the motion parallax obtained from the head coupling of perspective is more important than stereopsis in revealing structural information. Overall the results show that three times as much information can be perceived in the head coupled stereo view as in the 2D view

Franck, Glenn

Ware, Colin

English

UNH Scholars' Repository

University of New HampshireUniversity of New Hampshire Scholars' RepositoryCenter for Coastal and Ocean Mapping Center for Coastal and Ocean Mapping10-1994Viewing a Graph in a Virtual Reality Display isThree Times as Good as a 2D DiagramColin WareUniversity of New Hampshire, Durham, colin.ware@unh.eduGlenn FranckUniversity of New BrunswickFollow this and additional works at: https://scholars.unh.edu/ccomPart of the Computer Sciences Commons, and the Oceanography and Atmospheric Sciences andMeteorology CommonsThis Conference Proceeding is brought to you for free and open access by the Center for Coastal and Ocean Mapping at University of New HampshireScholars' Repository. It has been accepted for inclusion in Center for Coastal and Ocean Mapping by an authorized administrator of University of NewHampshire Scholars' Repository. For more information, please contact nicole.hentz@unh.edu.Recommended CitationWare, C.; Franck, G., "Viewing a graph in a virtual reality display is three times as good as a 2D diagram," in Visual Languages, 1994.Proceedings., IEEE Symposium on, pp.182-183, 4-7 Oct 1994 doi: 10.1109/VL.1994.363621Viewing a Graph in a Virtual Reality Display is Three Times as Good as a 2D Diagram Colin Ware and Glenn Franck Faculty of Computer Science, University of New Brunswick Box 4400, Fredericton, NB, Canada E3B 5A3, cware@unb.ca Abstract An experiment is reported which tests whether network information is more effectively displayed in a three dimensional space than in a two dimensional space. The experimental task is to trace a path in a network and the experiment is carried out in 2 0 ,  in a 3 0  stereo view, in a 3 0  view with head coupled perspective, and in a 3 0  stereo view with head coupled perspective: this last condition creates a localized virtual reality display. The results show that the motion parallax obtained from the head coupling of perspective is more important than stereopsis in revealing structural information. Overall the results show that three times as much information can be perceived in the head coupled stereo view as in the 2 0  view. 1. Introduction As the display of three dimensional rather than two dimensional information becomes commonplace due to advances in computer graphics hardware, the development of visual languages and symbologies that work in 3D will become increasingly important. One of the outstanding issues is the question of whether there is any advantage to creating visual languages that are truly three dimensional since the information is typically not spatial in nature. The present study addresses this issue by empirically testing the comprehension of network information shown in 3D and in 2D. A useful and interesting method for examining three dimensional structures is to couple a perspective stereoscopic view of a 3D scene to the user's eye positions and update the view in real-time as the user moves. The key elements of this are a high resolution monitor capable of running at a high frame rate, stereo glasses and some method for tracking the user's head position [1,2]. The position of the user's two eyes are computed from the head position and separate images are generated showing the correct perspective view of a set of virtual objects somewhere in the vicinity of the monitor screen. The result is a localized "Virtual Reality" (VR) environment which has a number of advantages over the much talked about immersive virtual reality, not the least of these being that the everyday workspace of desk, filing cabinet, co-workers and coffee mug are not excluded. In our previous work we have called this "Fish Tank VR" to characterize its localized nature and distinguish it from the full immersion kind [4]. 2. Experiment While it is clear that the kind of 3D display described above has advantages for people who wish to look at representations of 3D data, such as images of bones used for planning orthopaedic surgery, it is not clear that abstract data can benefit from 3D representation. The key question is, is a 3D diagram better than a 2D diagram? Some previous studies have suggested that there is and advantage but say nothing about how large the advantage is [1,3]. The purpose of this experiment was to determine how much more, or less, can be perceived in a head coupled stereo display used to display network information. On a given trial the subject viewed a randomly laid out network of nodes and arcs with two nodes highlighted. The task was to say if there was a path between the the highlighted nodes, while in fact there was either a path of length two or no path, each occurring 50% of the time. There were four viewing modes. 1) 2D: no stereo, no rotation; the 3D graph was projected onto a 2D plane using an orthographic (parallel) projection by removing Z axis information, hence no overlap information was available. 2) Stereo perspective: no rotation; this condition made use of a pair of StereoGraphics CrystalEyes LCD shutter glasses to provide the disparity depth cues. 3) Head coupled perspective: the scene's perspective projection changed continuously according to the subject's measured head position; the perspective projection was defined by a single viewpoint centered between the eyes. 4) Stereo, head coupled perspective: same as above, except with stereo; the correct view was generated for each eye position (continuously updated). The numbers of nodes used in the different conditions were as follows; these had been established as useful ranges in a previous pilot study. 182 0-8186-6660-9/94 $04.00 0 1994 IEEE 1) 21, 42, 63, 84, 105 2) 51, 81, 111, 141, 171 3) 81, 117, 153, 189, 225 4) 111, 156, 201,249,291 The number of arcs was the number of nodes multiply by 413. This experiment involved 11 participants. (The other procedure details are given in a technical report [ 5 ] . )  3. Results and discussion Figure 1 summarizes the error data from this experiment. This figure shows a sequence of curves with varying gradients which appear to be roughly multipliers of each other with respect to the graph size. That is, error rate appears to be directly proportional to the number of nodes, with a different gradient for the different conditions. To test this model we fitted a set of straight lines through the data with a zero intercept. These are shown as the broad lines running through the sets of points in Figure 4. Note that the vertical bars represent one standard error and that the true mean should lie outside of the range of two standard errors approximately five percent of the time. This very simple model appears to be a reasonable first approximation to the data, although as the errors approach 40% there appears to be some flattening of the curves. On the basis of these results we conclude that the graph that can be understood with head coupled stereo is about 3.0 times as large as the 2D graph for any given error rate (taking the ratios of the gradients). Using stereo alone appears to increase the comprehensible graph size by approximately a factor of 1.6 and using head coupling alone appears to increase the comprehensible graph size by a factor of 2.2. Many visual languages are networks of nodes connected by arcs. Because of the advantage of 3D viewing over 2D viewing, we can confidently predict that as high performance 3D graphics systems become commonplace, many visual languages will evolve from a 2D to a 3D layout. However, many challenging design problems will have to be solved in order to create symbology that works well in 3D. 1 .  2. 3.  4. 5 .  Arthur, K., Booth, K.S., and Ware, C. Evaluating Performance in Fish Tank Virtual Reality. ACM Transactions on Information Systrems. 1 l(3) 216-266. Deering, M. (1992) High resolution virtual reality. Computer Graphics, 26,2,195-202. Sollenberger, R.L and Milgram, P. (1993) The effects of Stereoscopic and Rotational Displays in  a Three- Dimensional Path-Tracing Task. Human Factors, 35(3) Ware, C., Arthur., and Booth, K.S. (1993)Fish Tank Virtual Reality. Proceedings of INTERCHIP3. 37-42. Ware, C. and Franck, G. (1994) Visualizing Information Nets in Three Dimensions. Technical Report, TR94-082, University of New Brunswick. 483-500. - 2D - Head Coupled Perspective -m- Stereo Perspective -rC- Stereo + Head Coupled 1 E W tR 50 40 30 20 10 0 I I I I 1 I 1 I I I I ! 0 100 200 300 Number of Nodes Figure 1. Error data from Experiments 1 a and 1 b. Vertical bars represent one standard error of the mean. The straight lines represent the simple model described in the text. 183 

Viewing a Graph in a Virtual Reality Display is Three Times as Good as a 2D Diagram

University of New Hampshire

University of New Hampshire
University of New Hampshire Scholars' Repository
Center for Coastal and Ocean Mapping Center for Coastal and Ocean Mapping
10-1994
Viewing a Graph in a Virtual Reality Display is
Three Times as Good as a 2D Diagram
Colin Ware
University of New Hampshire, Durham, colin.ware@unh.edu
Glenn Franck
University of New Brunswick
Follow this and additional works at: https://scholars.unh.edu/ccom
Part of the Computer Sciences Commons, and the Oceanography and Atmospheric Sciences and
Meteorology Commons
This Conference Proceeding is brought to you for free and open access by the Center for Coastal and Ocean Mapping at University of New Hampshire
Scholars' Repository. It has been accepted for inclusion in Center for Coastal and Ocean Mapping by an authorized administrator of University of New
Hampshire Scholars' Repository. For more information, please contact nicole.hentz@unh.edu.
Recommended Citation
Ware, C.; Franck, G., "Viewing a graph in a virtual reality display is three times as good as a 2D diagram," in Visual Languages, 1994.
Proceedings., IEEE Symposium on, pp.182-183, 4-7 Oct 1994 doi: 10.1109/VL.1994.363621
Viewing a Graph in a Virtual Reality Display is Three Times as Good as 
a 2D Diagram 
Colin Ware and Glenn Franck 
Faculty of Computer Science, University of New Brunswick 
Box 4400, Fredericton, NB, Canada E3B 5A3, cware@unb.ca 
Abstract 
An experiment is reported which tests whether network 
information is more effectively displayed in a three 
dimensional space than in a two dimensional space. The 
experimental task is to trace a path in a network and the 
experiment is carried out in 2 0 ,  in a 3 0  stereo view, in a 
3 0  view with head coupled perspective, and in a 3 0  stereo 
view with head coupled perspective: this last condition 
creates a localized virtual reality display. The results show 
that the motion parallax obtained from the head coupling 
of perspective is more important than stereopsis in 
revealing structural information. Overall the results show 
that three times as much information can be perceived in 
the head coupled stereo view as in the 2 0  view. 
1. Introduction 
As the display of three dimensional rather than two 
dimensional information becomes commonplace due to 
advances in computer graphics hardware, the development 
of visual languages and symbologies that work in 3D will 
become increasingly important. One of the outstanding 
issues is the question of whether there is any advantage to 
creating visual languages that are truly three dimensional 
since the information is typically not spatial in nature. 
The present study addresses this issue by empirically 
testing the comprehension of network information shown 
in 3D and in 2D. 
A useful and interesting method for examining three 
dimensional structures is to couple a perspective 
stereoscopic view of a 3D scene to the user's eye positions 
and update the view in real-time as the user moves. The 
key elements of this are a high resolution monitor capable 
of running at a high frame rate, stereo glasses and some 
method for tracking the user's head position [1,2]. The 
position of the user's two eyes are computed from the head 
position and separate images are generated showing the 
correct perspective view of a set of virtual objects 
somewhere in the vicinity of the monitor screen. The 
result is a localized "Virtual Reality" (VR) environment 
which has a number of advantages over the much talked 
about immersive virtual reality, not the least of these 
being that the everyday workspace of desk, filing cabinet, 
co-workers and coffee mug are not excluded. In our 
previous work we have called this "Fish Tank VR" to 
characterize its localized nature and distinguish it from the 
full immersion kind [4]. 
2. Experiment 
While it is clear that the kind of 3D display described 
above has advantages for people who wish to look at 
representations of 3D data, such as images of bones used 
for planning orthopaedic surgery, it is not clear that 
abstract data can benefit from 3D representation. The key 
question is, is a 3D diagram better than a 2D diagram? 
Some previous studies have suggested that there is and 
advantage but say nothing about how large the advantage 
is [1,3]. 
The purpose of this experiment was to determine how 
much more, or less, can be perceived in a head coupled 
stereo display used to display network information. On a 
given trial the subject viewed a randomly laid out network 
of nodes and arcs with two nodes highlighted. The task 
was to say if there was a path between the the highlighted 
nodes, while in fact there was either a path of length two 
or no path, each occurring 50% of the time. There were 
four viewing modes. 
1) 2D: no stereo, no rotation; the 3D graph was projected 
onto a 2D plane using an orthographic (parallel) 
projection by removing Z axis information, hence 
no overlap information was available. 
2) Stereo perspective: no rotation; this condition 
made use of a pair of StereoGraphics CrystalEyes 
LCD shutter glasses to provide the disparity depth 
cues. 
3) Head coupled perspective: the scene's perspective 
projection changed continuously according to the 
subject's measured head position; the perspective 
projection was defined by a single viewpoint 
centered between the eyes. 
4) Stereo, head coupled perspective: same as 
above, except with stereo; the correct view was 
generated for each eye position (continuously 
updated). 
The numbers of nodes used in the different conditions were 
as follows; these had been established as useful ranges in a 
previous pilot study. 
182 
0-8186-6660-9/94 $04.00 0 1994 IEEE 
1) 21, 42, 63, 84, 105 
2) 51, 81, 111, 141, 171 
3) 81, 117, 153, 189, 225 
4) 111, 156, 201,249,291 
The number of arcs was the number of nodes multiply by 
413. 
This experiment involved 11 participants. (The other 
procedure details are given in a technical report [ 5 ] . )  
3. Results and discussion 
Figure 1 summarizes the error data from this experiment. 
This figure shows a sequence of curves with varying 
gradients which appear to be roughly multipliers of each 
other with respect to the graph size. That is, error rate 
appears to be directly proportional to the number of nodes, 
with a different gradient for the different conditions. To 
test this model we fitted a set of straight lines through the 
data with a zero intercept. These are shown as the broad 
lines running through the sets of points in Figure 4. Note 
that the vertical bars represent one standard error and that 
the true mean should lie outside of the range of two 
standard errors approximately five percent of the time. 
This very simple model appears to be a reasonable first 
approximation to the data, although as the errors approach 
40% there appears to be some flattening of the curves. 
On the basis of these results we conclude that the graph 
that can be understood with head coupled stereo is about 
3.0 times as large as the 2D graph for any given error rate 
(taking the ratios of the gradients). Using stereo alone 
appears to increase the comprehensible graph size by 
approximately a factor of 1.6 and using head coupling 
alone appears to increase the comprehensible graph size by 
a factor of 2.2. 
Many visual languages are networks of nodes connected by 
arcs. Because of the advantage of 3D viewing over 2D 
viewing, we can confidently predict that as high 
performance 3D graphics systems become commonplace, 
many visual languages will evolve from a 2D to a 3D 
layout. However, many challenging design problems will 
have to be solved in order to create symbology that works 
well in 3D. 
1 .  
2. 
3.  
4. 
5 .  
Arthur, K., Booth, K.S., and Ware, C. Evaluating 
Performance in Fish Tank Virtual Reality. ACM 
Transactions on Information Systrems. 1 l(3) 216-266. 
Deering, M. (1992) High resolution virtual reality. 
Computer Graphics, 26,2,195-202. 
Sollenberger, R.L and Milgram, P. (1993) The effects of 
Stereoscopic and Rotational Displays in  a Three- 
Dimensional Path-Tracing Task. Human Factors, 35(3) 
Ware, C., Arthur., and Booth, K.S. (1993)Fish Tank 
Virtual Reality. Proceedings of INTERCHIP3. 37-42. 
Ware, C. and Franck, G. (1994) Visualizing Information 
Nets in Three Dimensions. Technical Report, TR94-082, 
University of New Brunswick. 
483-500. 
- 2D - Head Coupled Perspective 
-m- Stereo Perspective -rC- Stereo + Head Coupled 
1 
E 
W 
tR 
50 
40 
30 
20 
10 
0 
I I I I 1 I 1 
I I I I ! 
0 100 200 300 
Number of Nodes 
Figure 1. Error data from Experiments 1 a and 1 b. Vertical bars represent one standard error 
of the mean. The straight lines represent the simple model described in the text. 
183 


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Viewing a Graph in a Virtual Reality Display is Three Times as Good as a 2D Diagram

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