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OWL - The Optix 7 Wrapper Library

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Samples

Some sample projects/papers that recently used OWL:

• Moana on OWL/OptiX (Oct 2020)

  (https://ingowald.blog/2020/10/26/moana-on-rtx-first-light/)

  

• "VisII - A Python-Scriptable Virtual Scene Imaging Interface (2020)

  (https://github.com/owl-project/ViSII)

  

• “Ray Tracing Structured AMR Data Using ExaBricks”. I Wald, S Zellmann, W Usher, N Morrical, U Lang, and V Pascucci. IEEE TVCG(Proceedings of IEEE Vis 2020).

  (https://www.willusher.io/publications/exabrick)

  

• “Accelerating Force-Directed Graph Drawing with RT Cores”. S Zellmann, M Weier, I Wald, IEEE Vis Short Papers 2020.

  (https://arxiv.org/pdf/2008.11235.pdf)

• “A Virtual Frame Buffer Abstraction for Parallel Rendering of Large Tiled Display Walls”. M Han, I Wald, W Usher, N Morrical, A Knoll, V Pascucci, C R Johnson. IEEE Vis Short Papers 2020.

(http://www.sci.utah.edu/~wald/Publications/2020/dw2/dw2.pdf)

• “Spatial Partitioning Strategies for Memory-Efficient Ray Tracing of Particles”. P Gralka, I Wald, S Geringer, G Reina, Th Ertl. IEEE Symposium on Large Data Analysis and Viusalization (LDAV) 2020.

• “Finding Efficient Spatial Distributions for Massively Instanced 3-d Models”. S Zellmann, N Morrical, I Wald, V Pascucci. Eurographics Symposium on Parallel Graphics and Visualization (EGPGV 2020).

  (https://vis.uni-koeln.de/forschung/publikationen/finding-efficient-spatial-distributions-for-massively-instanced-3-d-models)

  

• “High-Quality Rendering of Glyphs Using Hardware-Accelerated Ray Tracing”. S Zellmann, M Aumüller, N Marshak, I Wald. Eurographics Symposium on Parallel Graphics and Visualization (EGPGV 2020).

  (https://vis.uni-koeln.de/forschung/publikationen/high-quality-rendering-of-glyphs-using-hardware-accelerated-ray-tracing)

  

• “RTX Beyond Ray Tracing: Exploring the Use of Hardware Ray Tracing Cores for Tet-Mesh Point Location”. I Wald, W Usher, N Morrical, L Lediaev, and V Pascucci. In High Performance Graphics Short Papers, 2019

  (https://www.willusher.io/publications/rtx-points)

• “Using Hardware Ray Transforms to Accelerate Ray/Primitive Intersections for Long, Thin Primitive Types”. I Wald, N Morrical, S Zellmann, L Ma, W Usher, T Huang, V Pascucci. Proceedings of the ACM on Computer Graphics and Interactive Techniques (Proceedings of High Performance Graphics), 2020

  (https://www.willusher.io/publications/owltubes)

• "Efficient Space Skipping and Adaptive Sampling of Unstructured Volumes Using Hardware Accelerated Ray Tracing. N Morrical, W Usher, I Wald, V Pascucci. In IEEE VIS Short Papers, 2019

  (https://www.willusher.io/publications/rtx-space-skipping)

OWL’s own “Tutorial-Style” Samples

The OWL repo itself contains a list of samples intended to only highlight/demonstrate certain individual technologies such as how to create a group, how to do multi-level instancing, etc. Here a overview over some of those:

ll08-sierpinski

The latest sample, demonstrating multi-level instancing:

• One geometry that contains exactly one pyramid

• N levels of instances, each of which creates four shifted and scaled instances of the previous level

• Number of levels configurable via command-line, via --num-levels <N>

ll07-groupOfGroups

ll06-rtow-mixedGeometries

• Extends ll05 by replacing some of the spheres with boxes

• Boxes are realized as triangle meshes, and organized in three different geometries (again, once per material).

• To support both boxes and user geometries this sample is the first to use two different groups (one triangle group, one user geom group)

• In this sample, device-code traces into the two different groups sequentially, then picks the closer of the two hitpoints

ll05-rtow

• The first-ever “real” example that re-implements Ingo Wald original OptiX-6 based “Ray Tracing in one Weekend” example with OWL.

• Three different CH programs - one each for Lambertian, Metal, and Dielectric.

• Spheres are organized in three different geometry groups (one per material type), each of which has multiple spheres.

• Material parameters are stored per-material, in a buffer per each geometry (i.e., the Lambertian spheres geom has a buffer of Lambertian material data, etc).

ll04-userGeometry-boundsProg

• Similar to ll03, except that bounds are computed via a bounding box program

• Bounds program specified in the device-program, and added to the user geometry type, then automatically run on device (on owl-allocated memory) when the accel structure needs rebuild (same as OptiX 6 bounds program).

ll03-userGeometry-boundsBuffer

• Replaces the triangle meshes in ll02 with user geometry

• User geometry uses an intersection program to implement a sphere shape

• in this sample, bounding box information for user geoms is passed via a (host-supplied) buffer of precomputed bounding boxes

ll02-multipleTriangleGroups

• Replaces single box with eight different ones

• Each box is its own triangle mesh, with its own SBT entry

• SBT entry stores the material data, closest-hit shader pulls this to shade boxes with different colors.

• Still one accel that contains all eight meshes

ll01-simpleTriangles

This was the very first sample ever implemented for OWL (at a time when OWL could do exactly this sample, and nothing else).

Key features:

• a single triangle mesh (the box) with a single SBT entry

• a single bottom-level acceleration structure

• a minimalistic miss program that uses launch index to compute the black-and-red-squares pattern

• a closest-hit program that computes geometry normal and dot N-dot-D shading.