Adam Phillippy Michael Schatz CMSC 838S April 4 th, D 2D vs. 3D

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

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

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

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

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

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).

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

Cone TreeCone 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 Information visualization using 3D interactive animation. Commun. ACM 36, 4 (Apr. 1993),

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

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 Information visualization using 3D interactive animation. Commun. ACM 36, 4 (Apr. 1993),

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 , Nov. 2000

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.

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?

2D Navigation 3 degrees of freedom 1. Up / Down 2. Left / Right 3. Rotate XY Input controls  Mouse (2)  Arrow keys (2)

3D Navigation 6 degrees of freedom 1. Forward / Back 2. Left / Right 3. Up / Down 4. Pitch (transverse axis) 5. Yaw (normal axis) 6. Roll (longitudinal axis) Input controls  Mouse + arrow keys (4)  Flight stick (5)  3D Mouse (6)  Body Reference Body Reference

Output Devices Flat monitor  Stereoscopic “3D” glasses  Relative motion Kinetic depth Motion parallax Eye tracking Head mounted Retinal displays Holographic

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

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

Spatial Memory Robertson’s Data MountainData Mountain  Leverage spatial abilities while keeping interaction simple  Faster and more accurate than IE4 Favorites

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 UIST’98, 1998, ACM Press

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?

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

2D vs. 3D Spatial Memory  Users surprised by their spatial memory  Subjective ratings Preferred physical over virtual Physically least cluttered: 2D > 2½D ≈ 3D Physically quickly found pages: 2D > 2½D > 3D 3D felt “cluttered” and “inefficient”

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

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

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 Why Not Make Interfaces Better than 3D Reality?. IEEE Comput. Graph. Appl. 23, 6 (Nov. 2003),

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