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Parallel Visualization Kenneth Moreland Sandia National Laboratories Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin.

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Presentation on theme: "Parallel Visualization Kenneth Moreland Sandia National Laboratories Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin."— Presentation transcript:

1 Parallel Visualization Kenneth Moreland Sandia National Laboratories Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energys National Nuclear Security Administration under contract DE-AC04-94AL85000.

2 The Parallel Visualization Pipeline Read Isosurface Reflect Render

3 The Parallel Visualization Pipeline Read Isosurface Reflect Render Read Isosurface Reflect Render Read Isosurface Reflect Render Read Isosurface Reflect Render

4 Data Parallel Pipelines Duplicate pipelines run independently on different partitions of data.

5 Data Parallel Pipelines Duplicate pipelines run independently on different partitions of data.

6 Data Parallel Pipelines Some operations will work regardless. Example: Clipping.

7 Data Parallel Pipelines Some operations will work regardless. Example: Clipping.

8 Data Parallel Pipelines Some operations will work regardless. Example: Clipping.

9 Data Parallel Pipelines Some operations will have problems. Example: External Faces

10 Data Parallel Pipelines Some operations will have problems. Example: External Faces

11 Data Parallel Pipelines Ghost cells can solve most of these problems.

12 Data Parallel Pipelines Ghost cells can solve most of these problems.

13 Data Partitioning Partitions should be load balanced and spatially coherent.

14 Data Partitioning Partitions should be load balanced and spatially coherent.

15 Data Partitioning Partitions should be load balanced and spatially coherent.

16 Load Balancing/Ghost Cells Automatic for Structured Meshes. Partitioning/ghost cells for unstructured is manual. Use the D3 filter for unstructured (Filters Alphabetical D3)

17 Partitioning on Spatial Structure: K-D Tree

18 K-D Trees Provide Query Structures What elements are closest to here?

19 Reconstructing Connectivity Information May not be unique. Neighbor info usually missing.

20 The Parallel Visualization Pipeline Read Isosurface Reflect Render Read Isosurface Reflect Render Read Isosurface Reflect Render Read Isosurface Reflect Render

21 Parallel Rendering

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23 Tiled Displays

24 Rendering Translucent Geometry

25 Unstructured Volume Rendering in Parallel

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30 Mesh Partitioning

31 K-D Trees Provide Query Structures What is the visibility order of the regions from this viewpoint?

32 ParaView Architecture for Interactive Remote Parallel Visualization Three Tier Data Server Render Server Client

33 Standalone Client Data Server Render Server

34 Client-Server Client Data Server Render Server Socket

35 Client-Render Server-Data Server Client Data Server Render Server Socket Socket × N

36 Client-Server Client Data Server Render Server Socket Minimize Communication Render Remotely Send Images

37 Rendering Modes Still Render Full detail render. Interactive Render Sacrifices detail for speed. Provides quick rendering rate. Used when interacting with 3D view.

38 Level of Detail (LOD) Geometric decimation. Used only with Interactive Render Original DataDivisions: 50x50x50Divisions: 10x10x10

39 Image Size LOD ParaViews parallel rendering overhead proportional to image size. To speed up interactive rendering, ParaView can render smaller sized images and inflate them. Original DataSubsample Rate: 2 pixelsSubsample Rate: 4 pixelsSubsample Rate: 8 pixels

40 Color Depth LOD Squirt is used to transfer images from server to client. Squirt is a run length encoder optimized for images. Run lengths improved by masking out some color bits. 24-bit mask19-bit mask10-bit mask

41 Summary Most visualization algorithms are embarrassingly parallel. Ghost cells can eliminate need for communication. Simulation dumps are often missing connectivity information. Geometry sizes grow quickly, image sizes dont. Sort-last rendering scales well in this regard. Avoid bottlenecks caused by saturating any process with geometry. Remote interactivity is important. Parallel resources are seldom local. Interactivity can be maintained with levels of detail. Always be clear what you are using. Make sure the full detail shows up eventually.


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