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PowerPointPrsentation

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scan each voxel along ray exactly once '3D-DDA' instead of actually performing an explicit intersection ... BINARY CLASSIFIED (CRISP) 'MULTI'-ISOSURFACES ... – PowerPoint PPT presentation

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Title: PowerPointPrsentation


1
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
2
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"

3
CUTTING PLANES / -SPHERES
Intuitive 3D-Interface for placing the
cutting-plane and cutting-sphere, respectively.
4
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

5
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

6
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

7
PENCIL SKETCH SHADING
8
RBS / ICS
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