PowerPointPrsentation

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d i r e c t v o l u m e r e n d e r e r
P H D V R
by Peter Houska
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CUBERILLE

• sample at grid-locations only
• scan each voxel along ray exactly once
• "3D-DDA" instead of actually performing an
  explicit intersection-calculation with each
  "voxel-cube"/cell
• nearest-neighbor interpolation (rounding by
  truncation) yields "cube-look"

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CUTTING PLANES / -SPHERES
Intuitive 3D-Interface for placing the
cutting-plane and cutting-sphere, respectively.
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PRECOMPUTED "3D - SHADOWMAPS"

• Preprocessed occlusion-data
• 32-bit per voxel with bits 31-16 for
  "occlusion-factor" so no big performance hit
  through additional mem-accesses to a 2nd buffer
• Just one additional lookup (2 mutiplies) during
  rendering for each voxel that needs to be drawn
  along each ray
• Shadow-map gets invalidated, when lightsource
  moves or transfer-function is altered considerably

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BINARY CLASSIFIED (CRISP)"MULTI"-ISOSURFACES

• Perform usual scan-steps as long as "sampled
  density" lt "desired isovalue"
• Employ binary search in the area of interest to
  increase accuracy

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TOONSHADING / EDGE DETECTION

• Z-Buffer is generated at no additional cost
  during ray-casting
• Process z-buffer as if it was a 2D-image (with
  horizontal and vertical edge-detector filters)
• Blend edges that were found with ray-casted
  color-informations

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PENCIL SKETCH SHADING
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RBS / ICS