Multiple volumetric datasets

Ray Casting of Multiple Volumetric Datasets with Polyhedral Boundaries on Manycore GPUs

SIGGRAPH ASIA 2009

2010/03/31

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Authors

Bernhard KainzPhD student

Markus GrabnerAssistant professor

Alexander BornikSenior researcher

Stefan HauswiesnerResearch assistant

Judith MuehlSenior researcher

Dieter SchmalstiegFull professor

Demo

Properties

Real-time frame-rates Many volumes Arbitrary polyhedral geometry CUDA implementation

A 20k polygons dragon with a 2563 brain volume

and nine 643 smoke clouds

Outline

Volume rendering with ray casting Depth sorting for polyhedral datasets Results

Outline

Volume rendering with ray casting Depth sorting for polyhedral datasets Results

Volume scattering

Multiple scattering

Volume scattering

Multiple scattering

Volume rendering integral

K(t): absorption coefficient

Volume rendering integral

K(t): absorption coefficient

Volume rendering integral

K(t): absorption coefficient

Volume rendering integral

K(t): absorption coefficient

Ray casting

Ray casting + empty space skipping

Ray casting + empty space skipping

Outline

Volume rendering with ray casting Depth sorting for polyhedral datasets Results

Flow-chart

Flow-chart

Triangle rasterization

Depth sorting

Integration

Triangle rasterizationFor a >=0 For a < 0

Triangle rasterization

y=0, n1(y)=1y=1, n1(y)=1y=2, n1(y)=1y=3, n1(y)=2

Use r0y=0, r(y)=0x0001y=1, r(y)=0x0010y=2, r(y)=0x0100y=3, r(y)=0x3000

For a >=0 For a < 0

Triangle rasterization

y=0, n1(y)=1y=1, n1(y)=1y=2, n1(y)=1y=3, n1(y)=2

Use r0y=0, r(y)=0x0001y=1, r(y)=0x0010y=2, r(y)=0x0100y=3, r(y)=0x3000

For a >=0 For a < 0

Depth sorting

Use 63 entries to keep depth order A entry contains

Z-value Triangle ID

Depth sorting + evaluation

Use 63 entries to keep depth order A entry contains

Z-value Triangle ID

81 depth data Their result Ground truth Errors > 5%

Outline

Volume rendering with ray casting Depth sorting for polyhedral datasets Results

Results

Roessler: shader code, C5 generates too large codeBrecheisen: can not handle >4 volumes

Results

Q&A

Thx.