A Bandwidth Effective Rendering Scheme for 3D Texture-based Volume Visualization on GPU

Transcription

1 for 3D Texture-based Volume Visualization on GPU Won-Jong Lee, Tack-Don Han Media System Laboratory ( Dept. of Computer Science, Yonsei University, Seoul, Korea

2 Contents Background & Proposed Octree-based Bandwidth Effective Volume Rendering al Results

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4 Why Volume Rendering? Overcome limitation of polygon-based rendering Volume rendering generate photorealistic and nonphotorealistic scene 3D Texture VR Limitation Polygon Dataset Polygonal Rendering Rendering Volume Dataset Volume Rendering Real Object

5 Application#1 Visualization 3D Texture VR Limitation material sciences geology medical visualization

6 Application#2 - Entertainment atmospheric effects 3D Texture VR Limitation explosions, FX game

7 3D Texture-base Volume Rendering Texture Based Volume-Rendering Low cost & high quality method 3D Texture VR Limitation X-ray like shading(1996) Shading with OpenGL extensions(1998) Shading with Register Combiner & Multi-Texture Units(1999) Classification with Multi-dimensional T/F(2001) GPU ray-casting (2003) Real-time decompression & rendering (2003) NPR for VR (2003) Point-based VR (2004)

8 3D Texture-base Volume Rendering Typical GPU-based volume rendering flow 3D Texture VR Limitation Gradient Computation Shaders and T/F Creation Main Original Volume Data CPU Disk Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

9 3D Texture-base Volume Rendering Typical GPU-based volume rendering flow 3D Texture VR Limitation Gradient Computation Shaders and T/F Creation Main Original Volume Data CPU Disk Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

10 3D Texture-base Volume Rendering Typical GPU-based volume rendering flow 3D Texture VR Limitation Gradient Computation Shaders and T/F Creation Main Original Volume Data CPU Disk Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

11 3D Texture-base Volume Rendering Typical GPU-based volume rendering flow 3D Texture VR Limitation Gradient Computation Shaders and T/F Creation Main Original Volume Data CPU Disk Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

12 3D Texture-base Volume Rendering Typical GPU-based volume rendering flow 3D Texture VR Limitation Gradient Computation Shaders and T/F Creation Main Original Volume Data CPU Disk Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

13 3D Texture-base Volume Rendering Typical GPU-based volume rendering flow 3D Texture VR Limitation Gradient Computation Shaders and T/F Creation Main Original Volume Data CPU Disk Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

14 Limitation of 3D Texture Mapping The size of volume data sets can be processed is still limited usually, MB graphic memory, middle sized(512 3 ) 8 16bit volume data, 256MB 512MB Gradient Computation Shaders and T/F Creation Main Original Volume Data CPU Disk Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation 3D Texture VR Limitation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

15 Limitation of 3D Texture Mapping Bottleneck in graphic memory bus lots of texture & pixel traffic (interpolation, α-blending) Lower localities in texture mapping & blending operation 3D Texture VR Limitation 1, request Pixel Gradient Computation Shader2,3,4 Hit! Shaders and T/F Creation 5,6,7,8, Miss!! Texture Threshing! 1,2,3,4 load u Main Graphic Original Volume Data CPU Disk t Vertex & Texture Coordinates Volume, Gradients, T/F, s Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

16 Limitation of 3D Texture Mapping Bottleneck in graphic memory bus lots of texture & pixel traffic (interpolation, α- blending) Lower localities in texture mapping & blending operation GPU Blending Unit Gradient Computation Pixel Shaders and T/F Creation Hit! Main Miss!! Original Volume Data CPU Disk Graphic Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation 3D Texture VR Limitation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

17 Limitation of 3D Texture Mapping Brute-forced approach classical optimization technique cannot be utilized (empty-space skipping, early-ray termination) 3D Texture VR Limitation unable to skip space Gradient Computation Shaders and T/F Creation Main Original Volume Data CPU Disk Vertex & Texture Coordinates Volume, Gradients, T/F, Graphic Pre-TnL Texture Pixel GPU Vertex Shader Post-TnL Triangle Setup And Rasterization Pixel Shader Raster Operation Coordinates Transform Classification, 3D Texture Mapping, Lighting Blending

18 Contributions of This Research Propose an sub-division based rendering algorithm for GPU bandwidth-effectiveness Enabling empty space skipping for optimized rendering Utilizing modern GPU features for low-cost texture coordinate computation Build-up for effective H/W simulation environments for GPU based rendering

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20 I.Boada, I.Navazo, and R.Scopigno. Multiresolution Volume Visualization with a Texture-Based Octree. The Visual Computer, 17(3), , VR on GPU Multi-resolution Empty Space Skipping AMR tree level (a) level (b) level (c)

21 W. Li, K. Mueller, and A. Kaufman, Empty Space Skipping and Occlusion Clipping for Texture-Based Volume Rendering, In Proc. of IEEE Visualization 2003, pages , VR on GPU Multi-resolution Empty Space Skipping AMR tree partitioned by the growing boxes converted into a BSP tree Rendering with mixed boxes and texture

22 R. Kauhler, M. Simon, and H. C. Hege, Interactive Volume Rendering of Large Sparse Data Sets Using Adaptive Mesh Refinement Hierarchies, IEEE Transactions on Visualization and Computer Graphics, VOL. 9, NO. 3, JULY-SEPTEMBER 2003, pages VR on GPU Multi-resolution Empty Space Skipping AMR tree Standard w/ Octree w/ AMR tree

23 Proposed Method

24 Proposed Octree-based V/R Octree based Empty Space Skipping Octree Hierarchy Rendering unable to skip empty space Sub-division enabling empty empty space space checking skipping standard method proposed method

25 Proposed Octree-based V/R Efficiency Octree Hierarchy Rendering standard method texture cache pixel cache proposed method texture cache pixel cache HIT HIT for each sub-volume MISS only cold MISS on switching sub-volume

26 Proposed Octree-based V/R Rendering Octree in GPU Utilizing the property of regular sized sub-volumes Easy to detect visibility order of each sub-volume Octree Hierarchy Rendering Incremental texture coordinates computations in GPU

27 al Results

28 Benchmarks Environment Analysis Texture Pixel Total Bandwidth Frame Rates Lobster (255x255x56) Engine (255x255x110) Foot (255x255x255) CTdata (255x255x255)

29 GPU Simulation Environment #1 CPU-based software simulation For evaluating cache efficiency, memory bandwidth compile with Cg compiler (cgc) Cg vertex & fragment shader NV_vertex_program NV_fragment_program GL function & shader assembly call Mesa 6.0 (fully compatible with OpenGL 1.5) Environment Analysis Texture Pixel Total Bandwidth Frame Rates C++ OpenGL application Dinero III scene cache simulation results Make comparison with standard and proposed method Under perfectly same cache configuration fully associative cache, 32Bytes block, 1~128KBytes cache 512x512 screen size, 10 frame rendered

30 GPU Simulation Environment #2 GPU-based hardware experiment For evaluating rendering speedup Cg vertex & fragment shader compile with Cg compiler (cgc) GL function call Environment Analysis Texture Pixel Total Bandwidth Frame Rates NV_vertex_program NV_fragment_program Standard OpenGL library (opengl32.dll) C++ OpenGL application GPU scene & frame rates result load Shader assembly to GPU Make comparison with standard and proposed method Under perfectly same condition Pentium IV 2.80GHz PC with 512MB RDRAM & AGP8x bus Nvidia GeForce FX 5900 with 256MB graphic memory

31 Trade-Off Analysis Average number of vertices per frame (K) lobster engine foot ctdata 256^3 128^3 64^3 32^3 16^3 8^3 The size of a sub-volume Non-empty region ratio lobster engine foot ctdata 256^3 128^3 64^3 32^3 16^3 8^3 The size of a sub-volume Environment Analysis Texture Pixel Total Bandwidth Frame Rates Average # of Vertices per Frame Non-Empty Region Ratio

32 Miss Rates Texture 20% NSD OSD(64^3) OSD(32^3) OSD(16^3) 20% NSD OSD(64^3) OSD(32^3) OSD(16^3) Miss Rate(%) 18% 16% 14% 12% 10% 8% 6% 4% 2% Miss Rate(%) 18% 16% 14% 12% 10% 8% 6% 4% 2% Environment Analysis Texture Pixel Total Bandwidth Frame Rates 0% Texture Size(KBytes) Lobster (255x255x56) 0% Texture Size(KBytes) Engine (255x255x110) NSD OSD(64^3) OSD(32^3) OSD(16^3) NSD OSD(64^3) OSD(32^3) OSD(16^3) 20% 20% 18% 18% 16% 16% 14% 14% Miss Rates(%) 12% 10% 8% Miss Rates(%) 12% 10% 8% 6% 6% 4% 4% 2% 2% 0% Texture Size(KBytes) Foot (255x255x255) 0% Texture Size(KBytes) CTdata (255x255x255) NSD : Non-Subdivided OSD : Octree Subdivided (number) : size of sub-volume

33 Miss Rates Pixel (Color) Miss Rate (%) NSD OSD(64^3) OSD(32^3) OSD(16^3) 5.5% 5.0% 4.5% 4.0% 3.5% 3.0% 2.5% 2.0% 1.5% 1.0% 0.5% Miss Rate (%) NSD OSD(64^3) OSD(32^3) OSD(16^3) 5.0% 4.5% 4.0% 3.5% 3.0% 2.5% 2.0% 1.5% 1.0% 0.5% Environment Analysis Texture Pixel Total Bandwidth Frame Rates 0.0% % Color Size (KB) Lobster (255x255x56) Color Size (KB) Engine (255x255x110) 5.5% 5.0% 4.5% NSD OSD(64^3) OSD(32^3) OSD(16^3) 5.0% 4.5% 4.0% NSD OSD(64^3) OSD(32^3) OSD(16^3) 4.0% 3.5% Miss Rate (%) 3.5% 3.0% 2.5% 2.0% 1.5% 1.0% 0.5% 0.0% Color Size (KB) Foot (255x255x255) Miss Rate (%) 3.0% 2.5% 2.0% 1.5% 1.0% 0.5% 0.0% Color Size (KB) CTdata (255x255x255) NSD : Non-Subdivided OSD : Octree Subdivided (number) : size of sub-volume

34 Miss Rates Pixel (Depth) 10% NSD OSD(64^3) OSD(32^3) OSD(16^3) 10% NSD OSD(64^3) OSD(32^3) OSD(16^3) Miss Rate (%) 9% 8% 7% 6% 5% 4% 3% 2% 1% Miss Rate (%) 9% 8% 7% 6% 5% 4% 3% 2% 1% Environment Analysis Texture Pixel Total Bandwidth Frame Rates 0% % Depth Size (KB) Lobster (255x255x56) Depth Size (KB) Engine (255x255x110) NSD OSD(64^3) OSD(32^3) OSD(16^3) NSD OSD(64^3) OSD(32^3) OSD(16^3) 10% 10% 9% 9% 8% 8% 7% 7% Miss Rate (%) 6% 5% 4% Miss Rate (%) 6% 5% 4% 3% 3% 2% 2% 1% 1% 0% Depth Size (KB) Foot (255x255x255) 0% Depth Size (KB) CTdata (255x255x255) NSD : Non-Subdivided OSD : Octree Subdivided (number) : size of sub-volume

35 Total Bandwidth Comparison #1 for 10 frames NSD : Non Sub-Divided standard method, OSD : Octree-based Sub-Divided method Environment Analysis Texture Pixel Total Bandwidth Frame Rates At best case, 29x reduced! Even worst case, 8Mbytes increased!

36 Total Bandwidth Comparison #2 for 10 frames Environment Analysis Texture Pixel Total Bandwidth Frame Rates

37 Rendering Performance Environment Analysis Texture Pixel Total Bandwidth Frame Rates NSD : Non Sub-Divided standard method, OSD : Octree-based Sub-Divided method

38 & Future work Octree based Bandwidth-Effective Volume Rendering Maximize the temporal & spacial locality of memory access Enable the empty space skipping 2~29x bandwidth reduction 2~6x faster rendering Application Volumetric Effects