1 / 11

Ray Tracing Dynamic Scenes with VLF-RT

Ray Tracing Dynamic Scenes with VLF-RT. Pankaj Khanna p.khanna@cs.ucl.ac.uk. Dynamics in a scene. Structured motion Animation of all polygons in dynamic object can be expressed by a single transformation matrix Unstructured motion Polygons of dynamic object undergo unrelated transformations.

jubal
Télécharger la présentation

Ray Tracing Dynamic Scenes with VLF-RT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ray Tracing Dynamic Scenes with VLF-RT Pankaj Khanna p.khanna@cs.ucl.ac.uk

  2. Dynamics in a scene • Structured motion • Animation of all polygons in dynamic object can be expressed by a single transformation matrix • Unstructured motion • Polygons of dynamic object undergo unrelated transformations BART Museum7 Scene: Jonas Lext, Ulf Assarsson, and Tomas Akenine-Möller, ``A Benchmark for Animated Ray Tracing'', IEEE Computer Graphics and Applications, pp. 22-31, March/April 2001. http://fibbla.ce.chalmers.se/BART/

  3. Changes to the VLF-RT data-structure • Each tile now has a linear list of dynamic polygons that overlap it • Currently a fixed-size array allocated on demand • Global frame-counter and local update-frame counter mechanism to track validity & updates

  4. Updating tiles on an animation change • Rasterization of dynamic polygons (in tile-space) at float-precision • Problems with integer-arithmetic rasterization • CPU vs GPU rasterization • Set tile’s update-frame counter to global counter • Multithreaded (1/2 PSFs each)

  5. On-demand tile updating • Updating a PSF’s tiles is only important if rays are to be tested along that PSF • Update a PSF on-demand if a ray is to be tested for intersection along it • Implicitly multi-threaded (as ray-tracing is multi-threaded) • Locking of updates (critical section) • Minimize locking by interleaved traversal of screen rows in top-down & bottom-up orders • Significant speed-up for Simple (false-colour) & OpenGL shading, marginal (or possibly negative) for Whitted

  6. Ray-intersection test • First intersect static scene using Tile-BSP scheme discussed earlier (for static VLF-RT) • Then intersect linear list of dynamic polygons in the corresponding tile • Alternative scheme to do dynamic first & then static could significantly reduce intersection-test time

  7. Intersecting dynamic polygons • Structured motion • Can use pre-processed information to use faster intersection kernel • Wald, I, “Realtime Ray Tracing and Interactive Global Illumination”, PhD Thesis, 2004 • Unstructured motion • Pre-processing not possible as polygons change shape/size/orientation per-frame • Currently using (slower) Möller-Trumbore intersection test • Tomas Möller and Ben Trumbore, “Fast, Minimum Storage Ray-Triangle Intersection”, Journal of Graphics Tools, Vol. 2, No. 1, pp. 21-28 1997.

  8. Results • Structured Motion • Video/Demo

  9. Results • Unstructured Motion • BART Video

  10. Limitations & Future-work • Currently dynamic objects must remain within confines of static scene • Currently polygons (triangles) only • Other primitives are possible if a fast 2D rasterisation & intersection can be performed • Alternate approach to represent structured dynamic object in its own VLF-RT space (with associated directions) so that coarse tile-updates will suffice

  11. Related publications • Khanna, P., Mortensen, J., Yu, I., Slater, M. (2004) A Visibility Field for Dynamic Ray Tracing, Technical Report, University College London • Khanna, P., Mortensen, J., Yu, I., Slater, M. (2004) Fast Ray Tracing of Scenes with Unstructured Motion, Technical Report, University College London • For these and other related work, see: http://www.cs.ucl.ac.uk/research/vr/Projects/VLF/Media/

More Related