Paper 3

1. Paper 3 Interactive Texture-Based Volume Rendering for Large Data Sets Joe Kniss University of Utah Patrick McCormick, Allen McPherson, James Ahrens, Jamie Painter, and Alan Keahey Los Alamos National Laboratory Charles Hansen University of Utah

2. Introduction • a scalable, pipelined approach for rendering data sets too large for a single graphics card. • 5 fps is considered near interactive rates. • 5 fps on a 128-CPU, 16-pipe SGI Origin 2000 with IR-2 graphics hardware. • Rendering isn’t bottleneck , I/O is. • Data is preprocessed and quantized from native datatype to 8 /12 bit unsigned integer data • Data then split into sub-volumes to fit available texture memory on graphics pipes.

3. TRex Pipeline

4. Pipeline ,I/O issues • Each stage is multi-threaded and has 2 main parts – event, functional managers • IO rates must match 300 MBps of texture download rates on IR pipes. • 16 parallel pipes -> 5Gbps • Practically 4Gbps reached – 4 channel fiber controller

5. Renderer, Compositor • A renderer initializes multiple image buffers for simultaneous rendering with the other stages because the compositing and user interface stages both rely on the image buffer • Gets messages from UI and uses 3D textures VAP or VCSS. • A Compositor begins once N renderers complete and composites back to front and done in software. • Pointer to renderer’s shared memory image buffer and sub-volume’s distance from eye point • A compositor is overwritten A=A+B.

6. Compositor

7. Overivew

8. Immersive TRex • Separate daemon • Stereo pairs . So half the resolution • Adaptive tessellation of spherical shells.