Ray Casting of Multiple Volumetric Datasets with Polyhedral Boundaries on Manycore GPUs - PowerPoint PPT Presentation

slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Ray Casting of Multiple Volumetric Datasets with Polyhedral Boundaries on Manycore GPUs PowerPoint Presentation
Download Presentation
Ray Casting of Multiple Volumetric Datasets with Polyhedral Boundaries on Manycore GPUs

play fullscreen
1 / 30
Ray Casting of Multiple Volumetric Datasets with Polyhedral Boundaries on Manycore GPUs
127 Views
Download Presentation
neil-weaver
Download Presentation

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

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Ray Casting of Multiple Volumetric Datasets with Polyhedral Boundaries on Manycore GPUs Park, Soonchan KAIST (Korea Advanced Institute of Science and Technology)

  2. Contents • Translucent object rendering • In Volumetric data rendering • In Polyhedral object rendering • Motivation & Goal of this paper • System Overview ( Pipeline ) • Triangle rasterization • Depth sorting • Ray casting of homogeneous segments • Empty space skipping • Results • Performance • Workload distribution • Memory consumption

  3. Contents • Translucent object rendering • In Volumetric data rendering • In Polyhedral object rendering • Motivation & Goal of this paper • System Overview ( Pipeline ) • Triangle rasterization • Depth sorting • Ray casting of homogeneous segments • Empty space skipping • Results • Performance • Workload distribution • Memory consumption

  4. How to Render Translucent Object • Rendering is totally different between data type • Volumetric data • Polyhedral object data • Brief explanation will follow • Volume Rendering • Polyhedral object Rendering

  5. Volume Data Set Examples

  6. Volume Rendering by Ray Casting Method Accumulated color of blue voxels = Color of pixel on view plane

  7. How to Render Translucency Object • Opacity transfer function • Example of gray value • Bone : over 1300 • Brain : 550~850 • Skin : 400~700

  8. Geometry data case • Back-to-Front order • Sort all geometry by z-value from camera • Render them from far to near • Depth peeling

  9. Depth Peeling

  10. Contents • Translucent object rendering • In Volumetric data rendering • In Polyhedral object rendering • Motivation & Goal of this paper • System Overview ( Pipeline ) • Triangle rasterization • Depth sorting • Ray casting of homogeneous segments • Empty space skipping • Results • Performance • Workload distribution • Memory consumption

  11. Motivation of this paper • It is needed • Multiple Volume Rendering • Rendering result of Volumetric data AND Polyhedral objects together • CSG Operations • Real time solution Customized Rendering Pipeline

  12. Goals • Implement Rendering method • for • Many volumes • Arbitrary polyhedral geometry • CSG operations(AND, OR, …) between them • By CUDA • Implement Pipeline • Control Memory management • Fully parallelized • In • Real-time

  13. ISSUES • How to Integrate two different method • How to Improve performance • Parallelize computation • Controlling Threads with scheduler (RR) • use GPU • Other optimization method

  14. Contents • Translucent object rendering • In Volumetric data rendering • In Polyhedral object rendering • Motivation & Goal of this paper • System Overview ( Pipeline ) • Triangle rasterization • Depth sorting • Ray casting of homogeneous segments • Empty space skipping • Results • Performance • Workload distribution • Memory consumption

  15. Pipeline

  16. System Overview • Triangle Rasterization • Depth Sorting • Ray casting of homogeneous segments • Empty space skipping

  17. 1. Triangle Rasterization

  18. 1. Triangle Rasterization • Parallel Computation • Rasterize triangle to screen • Make coverage masks • 1 or 0 (bit expression) • Each fragment unit(tile) hasinformation for triangles projected on them • Consider line slope and expresseach row as bit shifting  Four Times fasterthan straightforward per-pixel computation

  19. 2. Depth Sorting

  20. 2. Depth Sorting • For integrate with Ray casting method Array Triangle id 16bits Z-value 16bits

  21. 3. Ray casting of Homogeneous Segments &4. Empty Space Skipping

  22. 3. Ray casting of Homogeneous Segments • Pixel thread iterates through the sorted triangle array • Homogeneous Segments • Interval between two consecutive entries • We know currently intersected scene objects • CSG(boolean) operation can be applied

  23. 3. Ray casting of Homogeneous Segments • Only polyhedral objects loop can be simplified • No need to process whole ray casting step  Performance improvements of up to 10%

  24. 4. Empty Space Skipping • Processing rays in empty space is waste! • Calculating bounding geometries • By using lower resolution mask volume • Original Volume  Uniform bricks • Test underlying dataset voxel  Tight fitting bounding geometry improves frame rate by up to 15%

  25. Contents • Translucent object rendering • In Volumetric data rendering • In Polyhedral object rendering • Motivation & Goal of this paper • System Overview ( Pipeline ) • Triangle rasterization • Depth sorting • Ray casting of homogeneous segments • Empty space skipping • Results • Performance • Workload distribution • Memory consumption

  26. Results • Performance Comparison

  27. Results • Workload distribution

  28. Results

  29. Memory Consumption • Volume Texture ( 5283 ) • About 562 MB of global memory • Pre-computed gradient  x4 • Triangle Records • About 6MB • Complex scene  increase

  30. Conclusion • Good Performance • by recent improvements in multicore GPU • Customized Pipeline • Render in real-time • Broad range of applications • Multiple volumes • Volume data + Geometry data • CSG operation