Adam Phillippy

1
2D vs. 3D

• Adam Phillippy
• Michael Schatz
• CMSC 838S
• April 4th, 2005

2
2.1D Successes

• Modest use of 3D to add highlights to 2D
  interfaces
• Raised/Depressed Buttons
• Overlapping Windows Shadows
• Icons that resemble real-world objects
• Now a standard component of desktop metaphor

3
3D Success Stories

• Natural 3D Visualizations
• Medical Imagery, Architectural Drawing, Computer
  Assisted Design, Scientific Simulations
• Continuous variables, volumes, surfaces, inside
  and outside, left and right, below and above are
  intrinsically meaningful.
• Game Environments
• First person shooters, role playing fantasy,
  virtual 3D environments
• Increasingly rich social contexts based on social
  cognition

4
3D Failures

• Air-Traffic Control Systems (ambiguity)
• Hierarchical Browsing (occlusion, navigation)
• Line Bar Charts (distortion, ambiguity)
• Digital Library (poor search, linking)
• Desktops Workspaces (orientation)
• Web Browsing (screen space)

3D Issues
Interface Issues
5
3D Ambiguity

• Projective ambiguity
• 3D on a 2D display creates ambiguity in all 3
  dimensions
• 2D shadows help disambiguate x,y position

• Orientation ambiguity
• 3D models provide limited information
• Other icons may be necessary to resolve

6
Information Availability
Smallman, H. S., St. John, M., Oonk, H. M., and
Cowen, M. B. 2001. Information Availability in 2D
and 3D Displays. IEEE Comput. Graph. Appl. 21, 5
(Sep. 2001), 51-57.
7
Empirical Results

• Controlled experiment with 32 users performing
  search tasks across interfaces
• Confirmed results of a prior study (orange), but
  that study compared across information visibility
  styles in addition to 2D-3D differences.
• 2D is clear winner when comparing with consistent
  information visibility (green).

8
Hierarchical Data

• Rooted, Directed relationships
• File Systems, Organization Trees,
• Traditional Node-link diagrams require space
  proportional to number of children at different
  levels
• Overall aspect ratio grows exponentially with
  depth

9
Cone Tree Cam Tree

• The clearest win in this technology is
  interactive animation. It is easy to demonstrate
  that animation shifts cognitive load to the human
  perceptual system.

Robertson, G. G., Card, S. K., and Mackinlay, J.
D. 1993. Information visualization using 3D
interactive animation. Commun. ACM 36, 4 (Apr.
1993), 57-71.
10
Cone Tree

• Issues
• Occlusion
• Navigation
• Orientation
• Contrast with
• SpaceTree
• Same animation benefits
• TreeMap
• 1,000,000 node displays

11
Perspective Wall

• Details are presented with overview via
  fisheye-like zoom for linear data
• Sharp distortion at wall boundaries.

Robertson, G. G., Card, S. K., and Mackinlay, J.
D. 1993. Information visualization using 3D
interactive animation. Commun. ACM 36, 4 (Apr.
1993), 57-71.
12
XML3D

• Visualize the link structure for web sites using
  hyperbolic zoom.
• Support web content creators placing new content
  into existing hierarchy

Risden, K., Czerwinski, M., Munzner, T., Cook, D.
An initial examination of ease of use for 2D and
3D information visualizations of Web content,
International Journal of Human-Computer Studies,
v.53 n.5, p.695-714, Nov. 2000
13
XML3D Empirical Study

• Controlled Experiment with 16 users and 4 tasks.
• Measure performance relative to 2D hierarchical
  displays (Windows Explorer).
• Statistically significant performance improvement
  for search tasks when category is present.

14
3D or not 3D

• Input
• Mice offer only 2 degrees of freedom
• Output
• Screens are planar
• User cognition
• Naturally operate in 3D world
• Awareness, perception, reasoning, and judgment
• Costs and benefits?

15
2D Navigation

• 3 degrees of freedom
• Up / Down
• Left / Right
• Rotate XY
• Input controls
• Mouse (2)
• Arrow keys (2)

16
3D Navigation

• 6 degrees of freedom
• Forward / Back
• Left / Right
• Up / Down
• Pitch (transverse axis)
• Yaw (normal axis)
• Roll (longitudinal axis)
• Input controls
• Mouse arrow keys (4)
• Flight stick (5)
• 3D Mouse (6)
• Body Reference

17
Output Devices

• Flat monitor
• Stereoscopic
• 3D glasses
• Relative motion
• Kinetic depth
• Motion parallax
• Eye tracking
• Head mounted
• Retinal displays
• Holographic

18
Coupled Input/Output

• Ware and Franck
• Find path of length 2 between 2 nodes
• 2D projection
• 26 error
• 3D stereo with tracking
• 8 error
• Timings roughly similar
• Limited interaction
• Head/hand coupled
• Motion was effective, but timing suffered

19
Summary

• Positives
• 3D information visualization has promise
• Eye tracking for parallax effect
• Stereo for depth
• Missing features
• 3D input device for rotation
• Negatives
• Uncomfortable for user
• Hardware not widely accessible

C. Ware and G. Franck, Evaluating Stereo and
Motion Cues for Visualizing Information Nets in
Three Dimensions, ACM Trans. Graphics, vol. 15,
no. 2, 1996, pp. 121-139.
20
Spatial Memory

• Robertsons Data Mountain
• Leverage spatial abilities while keeping
  interaction simple
• Faster and more accurate than IE4 Favorites

21
Summary

• Positives
• Leverages spatial and image memory
• Users remembered their layout after several
  months!
• Simple navigation (point and click)
• Keeps user orientated at all times
• Limits occlusion and clutter
• Keeps text readable via pop-ups
• 3D audio enhances sense of depth
• Missing features
• Auto alignment
• X-ray vision
• Dynamic filters

G. Robertson et al., Data Mountain Using
Spatial Memory for Document Management,
Proceedings of UIST98, 1998, ACM Press. 153-162.
22
2D vs. 3D Spatial Memory

• Where did I
• Leave Firefox?
• 2D window manager
• Park my car?
• 2D (2½D) parking lot
• Park my spaceship?
• 3D space
• Which is the most effective for memory?

23
2D vs. 3D Spatial Memory

• Cockburn and McKenzie
• Compare 2D vs. 2½D vs. 3D Data Mountain
• Both virtual and physical interfaces

24
2D vs. 3D Spatial Memory

• Users surprised by their spatial memory
• Subjective ratings
• Preferred physical over virtual
• Physically least cluttered 2D gt 2½D 3D
• Physically quickly found pages 2D gt 2½D gt 3D
• 3D felt cluttered and inefficient

25
Summary

• Skeptical of 3D document retrieval
• As dimensionality increased
• Speed decreased
• User preference decreased
• Spatial memory clearly effective
• But...
• 3D hindered retrieval, even in the physical world

A. Cockburn, B. McKenzie, Evaluating the
Effectiveness of Spatial Memory in 2D and 3D
Physical and Virtual Environments, Proc. ACM
Computer-Human Interaction Conf. Human Factors in
Computing Systems, ACM Press, 2002, pp.203-210
26
Representation Matters
W. Ark, et al., Representation Matters The
Effect of 3D Objects and a Spatial Metaphor in a
Graphical User Interface, Proc. Human-Computer
Interaction Conf. People and Computers XIII,
Springer-Verlag, 1998, pp.209-219.
27
Information Visualization Success

• Success is often due to design features that make
  the interfaces even better than reality
• Interface controls are as important as the
  graphics display
• Metrics help guide design
• Usability testing is essential
• it might be more important to fight for two
  versus three clicks than to debate 2D versus 3D.

Shneiderman, B. 2003. Why Not Make Interfaces
Better than 3D Reality?. IEEE Comput. Graph.
Appl. 23, 6 (Nov. 2003), 12-15.
28
3D Guidelines

• Use occlusion, shadows, perspective carefully
• Minimize the number of navigation steps for users
  to accomplish their tasks
• Keep text readable
• Avoid unnecessary visual clutter, distractions,
  contrast-shifts and reflections
• Simplify user and object movements
• Organize groups of items in aligned structures to
  allow rapid visual search
• Enable users to construct visual groups to
  support spatial recall
• Allow teleportation, x-ray vision