3D Information

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3-D Information

• cs5764 Information Visualization
• Chris North

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Where are we?

• Multi-D
• 1D
• 2D
• 3D
• Hierarchies/Trees
• Networks/Graphs
• Document collections

• Design Principles
• Empirical Evaluation
• Navigation Strategies
• Visual Overviews

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3-D Information Examples

• Universe, space
• CAD/CAM, architecture
• Physical objects, atomic structures, scientific
  data
• physiological, MRI

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Types of 3-D Information

• Surface data
• 2D analogy vector graphics, geometric shapes
• Volume data
• 2D analogy raster graphics, bitmaps, images

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Surface Data

• Vector/Polygonal surface data
• Polygons approximate surfaces of 3D objects
• Paint textures on surfaces
• Examples
• Quake

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VRML

• Protein example
• http//www.rcsb.org/pdb/cgi/explore.cgi?jobgraphi
  cspdbId4TNApagepid16250983503380

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Navigation
y

• Move camera (POV)
• Move objects
• 6 degrees of freedom (DOF)
• 3 translation
• 3 rotation
• Zoom translate forward?

x
z
y
x
z
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Zoom vs. Translation
zoom
translate
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Graphics

• Projection
• Z-buffer
• Shading, texture mapping,
• Ray Tracing
• Shoot rays from camera into scene
• Reflection,

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Challenges

• Navigation
• DOF
• Zoom, OD, FC?
• Occlusion, See inside?
• Manipulation

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OverviewDetail

• Stoakley, Worlds in Miniature

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Volume Data
2-D

• 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

3-D
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The Problem

• E.g. the Visible Human
• Whats inside?

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Slicing

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

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Slice and Dice
OverviewDetail
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3D Cutting Plane

• Ken Hinckley, UVA

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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

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Volume Rendering

• Ray Casting
• Like x-ray
• Accumulate color opacity along rays
• Transfer functions
• Splatting
• Like projection
• Reverse of ray-casting
• Calculate each voxels contribution to image

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Interactive Volume Rendering

• Kniss, Interactive volume rendering with direct
  manipulation

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Transparency X-Ray Vision

• Surface Volume
• http//www.uke.uni-hamburg.de/institute/imdm/idv/v
  m3dn/io_xray_combined.en.html
• http//graphics.stanford.edu/software/volpack/movi
  es/vp_movies.html

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Combining it all together

• Voxel-Man
• Hamburg University
• http//www.uke.uni-hamburg.de/institute/imdm/idv/v
  m3dn/io_thorax.en.html

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3-D volume data Digital Video

• 3D Stack 2D video frames

time
y
x
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Slicing Digital Video
Full overview
time
zoom

• Reds Nightmare video in VHE
• http//vtopus.cs.vt.edu/north/infoviz/RedsNightma
  re.mpg

motion
Scene change
Pan left
still
credits