1. 3-D Information cs5764: Information Visualization Chris North

2. Where are we? Multi-D 1D 2D 3D Hierarchies/Trees Networks/Graphs Document collections Design Principles Empirical Evaluation Navigation Strategies Visual Overviews

3. 3-D Information Examples Universe, space CAD/CAM, architecture Physical objects, atomic structures, scientific data physiological, MRI

4. Types of 3-D Information Surface data 2D analogy: vector graphics, geometric shapes Volume data 2D analogy: raster graphics, bitmaps, images

5. Surface Data Vector/Polygonal surface data Polygons approximate surfaces of 3D objects Paint textures on surfaces Examples: Quake

6. VRML Protein example http://www.rcsb.org/pdb/cgi/explore.cgi?job=graphics&pdbId=4TNA&page=&pid=16250983503380

7. Navigation Move camera (POV) Move objects 6 degrees of freedom (DOF): 3 translation 3 rotation Zoom = translate forward? y z x x y z

8. Zoom vs. Translation zoomtranslate

9. Graphics Projection Z-buffer Shading, texture mapping, … Ray Tracing Shoot rays from camera into scene Reflection, …

10. Challenges Navigation DOF Zoom, O+D, F+C? Occlusion, See inside? Manipulation

11. Overview+Detail Stoakley, “Worlds in Miniature”

12. Volume Data Voxel volume data Fully sampled contents of 3D objects Voxel = 3D pixel; tiny cube in a 3D image Volume = 3D array of voxels Examples: MRI, CaT scan: »Measures tissue density at each point in space Visible Human »slice and photograph The problem: 2-D: 3-D:

13. The Problem E.g. the Visible Human What’s inside?

14. Slicing Visible Human Explorer (north et al) http://www.cs.umd.edu/hcil/visible-human/vhp.mpg

15. Slice and Dice Overview+Detail

16. 3D Cutting Plane Ken Hinckley, UVA

17. Surface Reconstruction Generate surface data from volume data Iso-surfaces Marching Cubes algorithm Look at cubes of 8 voxels Cube is on surface if: ??? Generate polygons Smooth

18. Volume Rendering Ray Casting Like x-ray Accumulate color & opacity along rays “Transfer functions” Splatting Like projection Reverse of ray-casting Calculate each voxel’s contribution to image

19. Interactive Volume Rendering Kniss, “Interactive volume rendering with direct manipulation”

20. Transparency: X-Ray Vision SurfaceVolume http://www.uke.uni-hamburg.de/institute/imdm/idv/vm3dn/io_xray_combined.en.html http://graphics.stanford.edu/software/volpack/movies/vp_movies.html

21. Combining it all together Voxel-Man Hamburg University http://www.uke.uni-hamburg.de/institute/imdm/idv/vm3dn/io_thorax.en.html

22. 3-D volume data: Digital Video 3D: Stack 2D video frames time x y

23. Slicing Digital Video Red’s Nightmare video in VHE http://vtopus.cs.vt.edu/~north/infoviz/RedsNightmare.mpg Full overview: time zoom Scene change still credits motion Pan left