Pre-Integrated Volume-Rendering with Randomized Transfer-Functions (V3D2 Workshop 2002)

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Usage of volume rendering techniques in Chemitry and Medicine
V3D2 Workshop 2002, Braunschweig,
Strategic DFG research initiative "V3D2" ("Distributed Processing and Exchange of Digital Documents")

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Pre-Integrated Volume-Rendering with Randomized Transfer-Functions (V3D2 Workshop 2002)

  1. 1. Pre-Integrated Volume-Rendering with Randomized Transfer-Functions Klaus Engel, Guido Reina, Thomas Ertl Klaus Engel, Guido Reina, Thomas Ertl Abteilung Visualisierung und Interaktive Systeme Abteilung Visualisierung und Interaktive Systeme Universität Stuttgart Universität Stuttgart Frank Oellien, W.D. Ihlenfeldt Frank Oellien, W.D. Ihlenfeldt Computer Chemie Centrum Computer Chemie Centrum Universität Erlangen-Nürnberg Universität Erlangen-Nürnberg V3D2 Symposium 21./22. Februar 2002
  2. 2. Volume Data Sources Measurements (cryo-electron microscopy) Binning of multi-variate data Computed data (molecular orbitals) Simulations (convection flow) Synthetic data (radial distance volume + Perlin Noise) V3D2 Symposium 2002 - ChemVis Project
  3. 3. Volume Rendering - Physical Model • Physics of light transport • Simplified to Volume Rendering Integral I ( s) = I ( s0 )e −τ ( s0 , s ) s2 s + ³ q( s' ) ⋅ e −τ ( s ', s ) ds' s0 τ ( s1, s2 ) = ³ κ ( s)ds s1 • Transfer Function: Assigns opacity and color • s s0 • Discretization n j =i +1 d d d n i =0 d I (sn ) = ¦ Ciα i ∏ (1 − α j ) s1 V3D2 Symposium 2002 - ChemVis Project sn
  4. 4. Texture-based Volume Rendering 2D textures (axis-aligned slices) texturing (bilinear interpolation) compositing (blending) texturing (trilinear interpolation) compositing (blending) 3D textures (view-aligned Slices) V3D2 Symposium 2002 - ChemVis Project
  5. 5. Volume Rendering - Classification Classification Interpolation Transfer-Functions Pre-Classification Voxel Interpolation Classification Post-Classification V3D2 Symposium 2002 - ChemVis Project
  6. 6. Higher Sampling Rates Cryoelectron-microscopic Volume Isosurface of Escherichia Coli Ribosome at 18 Ångström All data slices V3D2 Symposium 2002 - ChemVis Project 10 times more slices
  7. 7. Higher Sampling Rates – Problem • Discrete Approximation of Volume Rendering Integral will converge to correct result for d→0 – According to Sampling Theorem sampling rate must be greater than the Nyquist frequency – But: High frequencies in the Transfer Function may considerably increase the required sampling rate • Pre-Integrated Volume Rendering – Idea: Split numerical integration into • one pre-integration for the transfer function • one integration for the scalar field – Pre-Integrate Ray-Segments in a pre-processing step V3D2 Symposium 2002 - ChemVis Project
  8. 8. Pre-Integrated Volume Rendering slice-by-slice slab-by-slab project slice sf sb texture polygon pre-integrate all fetch integral from possible combinations s dependent texture b sb sf sb sf sf front back slice slice hardware-accelerated implementation on NVidia NV20 and ATI R200 chips V3D2 Symposium 2002 - ChemVis Project
  9. 9. Single Peaked Transfer-Functions V3D2 Symposium 2002 - ChemVis Project
  10. 10. Multi-Peak Transfer-Functions V3D2 Symposium 2002 - ChemVis Project
  11. 11. Randomized Transfer-Functions V3D2 Symposium 2002 - ChemVis Project
  12. 12. Randomized Transfer-Functions V3D2 Symposium 2002 - ChemVis Project
  13. 13. Results – Classification schemes Pre-Classification Post-Classification Pre-Integrated-Classification V3D2 Symposium 2002 - ChemVis Project
  14. 14. Results - OrbVis V3D2 Symposium 2002 - ChemVis Project
  15. 15. Results – Randomized Transfer Functions V3D2 Symposium 2002 - ChemVis Project
  16. 16. Results – Randomized Transfer Functions V3D2 Symposium 2002 - ChemVis Project
  17. 17. Results – Randomized Transfer Functions V3D2 Symposium 2002 - ChemVis Project
  18. 18. Conclusions • Pre-Integrated Volume Rendering – – – – hardware-accelerated Implementation integration into digital documents ? reproduces high frequencies in the TFs ideally suited for random TFs • Randomized Transfer Functions – a new visualization technique for volume data – somehow related to LIC – visualizes “all” isosurfaces at the same time V3D2 Symposium 2002 - ChemVis Project
  19. 19. InfoVis - Previous Work VRML-based NCI Database Interface detailed structure information substructure search NCI anti-viral anti-tumor database results toxicity (LD50) of chemical compounds against breast cancer cell lines V3D2 Symposium 2002 - ChemVis Project
  20. 20. Current Work InfVis Applet I Tool Panel Java3D Canvas (filters, selection tools, details) Control Panel Glyph-based (details) + volumetric (overview) V3D2 Symposium 2002 - ChemVis Project
  21. 21. Future Worker Guido Reina: „Visualisierung und Manipulation großer Graphen in einem Graphical User Interface am Beispiel der zSeries I/O-Topologie” V3D2 Symposium 2002 - ChemVis Project

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