3-D Data cs5984: Information Visualization Chris North
Dec 13, 2015
3-D Data
cs5984: Information Visualization
Chris North
Review
• Visualizing document collections:•
Where are we?
• Multi-D• 1D• 2D• Hierarchies/Trees• Networks/Graphs• Document collections• 3D
• Design Principles• Empirical Evaluation• Java Development• Visual Overviews• Multiple Views• Peripheral Views
3-D Data
• Surface data
• Volume data
Surface Data
• Vector/Polygonal surface data• Polygons approximate surfaces of 3D objects
• Paint textures on surfaces
• Examples:• Quake
•
VRML
• Protein example• http://www.rcsb.org/pdb/cgi/explore.cgi?job=graphics&pdbId=4TNA&page=&pid=16250983503380
Navigation
• Move camera
• Move objects
• 6 degrees of freedom:• 3 translation
• 3 rotation
• Zoom = translate forward?
y
z
x
x
y
z
Zoom
Graphics
• Projection• Z-buffer
• Shading, texture mapping, …
• Ray Tracing• Shoot rays from camera into scene
• Reflection, …
Challenges
• Navigation
• Occlusion, See inside?
Volume Data
• Voxel volume data• Fully sampled contents of 3D objects
• Voxel = 3D pixel; point in a 3D image
• Volume = 3D array
• Examples:• MRI, CaT scan:
» Measures tissue density at each point in space
• Visible Human» slice and photograph
2-D:
3-D:
Slicing
• Visible Human Explorer (north et al)• http://www.cs.umd.edu/hcil/visible-human/vhp.mpg
Slice and Dice
3D Cutting Plane• Ken Hinckley, UVA
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
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
Transparency: X-Ray Vision
Surface Volumehttp://www.uke.uni-hamburg.de/institute/imdm/idv/vm3dn/io_xray_combined.en.html
http://graphics.stanford.edu/software/volpack/movies/vp_movies.html
Combining it all together
• Voxel-Man• Hamburg University• http://www.uke.uni-hamburg.de/institute/imdm/idv/vm3dn/io_thorax.en.html
Interactive Volume Rendering
• Kniss, “Interactive volume rendering with direct manipulation”
• Xueqi, Mahesh
3-D volume data: Digital Video
• 3D: Stack 2D video frames
time
x
y
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
Assignment• Thurs: Workspaces
• Robertson, “Task Gallery”» supriya, varun
• Upson, “AVS”» christa, jun
• Dec 7: ACM CHI short papers due
• Dec 18: Project Final Paper due
• March: IEEE InfoVis papers due
Future
• Thanksgiving break
• Tues 27: Debates, 2D vs 3D• Kobsa, “Empirical comparison of comm infovis systems”
» kunal, zhiping
• Thurs 29: How (not) to lie with visualization• Other fun stuff?
Project Presentations
• Dec 4:
• Dec 6:
• Dec 11:
Upcoming Opportunities
• Independent studies
• Thesis projects
• GTAs
• GRAs