OptiX

<h2 id="ray-tracing-with-optix">Ray tracing with OptiX</h2>

<p>OptiX works by using user-supplied instructions (in the form of <a href="/facts/CUDA/fvPpolot">CUDA</a> kernels) regarding what a ray should do in particular circumstances to simulate a complete tracing process.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>
</p><p>A light ray (or perhaps another kind of ray) might have a different behavior when hitting a particular surface rather than another one, OptiX allows to customize these hit conditions with user-provided programs. These programs are written in CUDA C or directly in <a href="/facts/Parallel_Thread_Execution/Caootlhz">PTX</a> code and are linked together when used by the OptiX engine.
</p><p>In order to use OptiX a CUDA-capable <a href="/facts/GPU/PTK1RQVp">GPU</a> must be available on the system and the CUDA toolkit must be installed.
</p><p>Using the OptiX engine in a ray tracing application usually involves the following steps:
</p>
<ul><li>Defining programs for ray generation (e.g. rays can be shot in parallel, in a <a href="/facts/Perspective_(graphical)/zkNx7Wpf">perspective</a> fashion or like a <a href="/facts/Gradient/TsR7uukj">gradient</a> field), ray missing (when a ray doesn't intersect any object), an optional exception program (when the ray cannot be shot for some reason), a <a href="/facts/Bounding_box/oFHL8bxI">bounding box</a> program (the program that provides a bounding box intersection test for a given object) and an intersection program.</li></ul>
<p>Several examples for these programs are available with the program's <a href="/facts/Software_development_kit/2Hkk6Hbs">SDK</a>
</p>
// Sample code using OptiX APIs //

/* Ray generation program */
rtProgramCreateFromPTXFile( *context, path_to_ptx, "pinhole_camera", &ray_gen_program );
rtContextSetRayGenerationProgram( *context, 0, ray_gen_program );

/* Miss program */
rtProgramCreateFromPTXFile( *context, path_to_ptx, "miss", &miss_program );
rtContextSetMissProgram( *context, 0, miss_program );

/* Bounding box and intersection program */
rtProgramCreateFromPTXFile( context, path_to_ptx, "box_bounds", &box_bounding_box_program );
rtGeometrySetBoundingBoxProgram( *box, box_bounding_box_program );
rtProgramCreateFromPTXFile( context, path_to_ptx, "box_intersect", &box_intersection_program );
rtGeometrySetIntersectionProgram( *box, box_intersection_program );

<p>Bounding box programs are used to define bounding volumes used to accelerate ray tracing process within acceleration structures as <a href="/facts/Kd-tree/XuhcfKKq">kd-trees</a> or <a href="/facts/Bounding_volume_hierarchies/1FBFkwNe">bounding volume hierarchies</a>
</p>
<ul><li>Create material any hit and closest hit programs: these two programs determine a ray behavior when encountering its first intersection (closest hit) or a generic intersection (any hit)</li></ul>
// Sample code using OptiX APIs //

rtProgramCreateFromPTXFile( context, path_to_ptx, "closest_hit_radiance", &closest_hit_program );
rtProgramCreateFromPTXFile( context, path_to_ptx, "any_hit_shadow", &any_hit_program );

/* Associate closest hit and any hit program with a material */
rtMaterialCreate( context, material );
rtMaterialSetClosestHitProgram( *material, 0, closest_hit_program );
rtMaterialSetAnyHitProgram( *material, 1, any_hit_program );

<ul><li>Define <a href="/facts/Data_buffer/tVy4j2Dc">buffers</a>, <a href="/facts/Variable_(computer_science)/VoCKtwml">variables</a> that might be used inside the supplied programs. Buffers are memory areas that allow host code (i.e. normal <a href="/facts/CPU/Jxp1bqMV">CPU</a> code) to communicate with device code (i.e. the code that gets executed on the GPU) and vice versa. Variables are OptiX's internal way of communicating and using buffers to transfer data back and forth.</li>
<li>Define the OptiX hierarchy of geometry objects, groups, selectors and other nodes to generate a tree graph of the entire scene to be rendered</li></ul>

<p>In order to render a complex scene or trace different paths for any ray OptiX takes advantage of <a href="/facts/GPGPU/roBwsPY2">GPGPU</a> computing by exploiting Nvidia CUDA platform.
Since the process of shooting rays and setting their behavior is highly customizable, OptiX may be used in a variety of other applications aside from ray tracing.
</p>
<h2 id="optix-prime">OptiX Prime</h2>
<p>Starting from OptiX 3.5.0 a second library called OptiX Prime was added to the bundle which aims to provide a fast low-level <a href="/facts/API/GMlN4vUr">API</a> for ray tracing - building the <a href="/facts/Bounding_volume_hierarchy/1FBFkwNe">acceleration structure</a>, traversing the acceleration structure, and <a href="/facts/M%25C3%25B6ller%25E2%2580%2593Trumbore_intersection_algorithm/Er8K0h82">ray-triangle intersection</a>. Prime also features a CPU fallback when no compatible GPU is found on the system. Unlike OptiX, Prime is not a programmable API, so lacks support for custom, non-triangle primitives and shading. Being non-programmable, OptiX Prime does not encapsulate the entire algorithm of which ray tracing is a part. Thus, Prime cannot recompile the algorithm for new GPUs, refactor the computation for performance, or use a network appliance like the Quadro VCA, etc.
</p>
<h2 id="software-using-optix">Software using OptiX</h2>
<ul><li><a href="/facts/Blender_(software)/yzuvB0fL">Blender</a> has OptiX support since version 2.81 (7.1 in 2.92) <a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></li>
<li>The Blender Add-on <a href="https://remington.pro/software/blender/d-noise/">D-NOISE</a> uses OptiX binaries for AI-accelerated denoising<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></li>
<li>At <a href="/facts/SIGGRAPH/gmRKkIlG">SIGGRAPH</a> 2011 <a href="/facts/Adobe_Systems/Bj1d5XvJ">Adobe</a> showcased OptiX in a technology demo of GPU ray tracing for motion graphics.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></li>
<li>At <a href="/facts/SIGGRAPH/gmRKkIlG">SIGGRAPH</a> 2013 OptiX was featured in <a href="/facts/Pixar/McUyzor2">Pixar</a>'s realtime, GPU-based lighting preview tool.</li>
<li>OptiX has been integrated into the <a href="/facts/Nvidia_GameWorks/yEazqNyb">GameWorks</a> developers library along with <a href="/facts/PhysX/FabGhdvx">PhysX</a> and other <a href="/facts/CUDA/fvPpolot">CUDA</a> powered graphics engines and frameworks.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></li>
<li><a href="/facts/Adobe_After_Effects/Xr4G0bjX">Adobe After Effects</a> CC<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a></li>
<li><a href="/facts/Daz_Studio/l1SMRDks">Daz Studio</a> had OptiX Prime Acceleration since its Iray integration, however support was removed in version 4.12.1.8<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></li>
<li><a href="/facts/Luxrender/pYQNxN0B">Luxrender</a> 2.5: up to 600% acceleration <a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></li></ul>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/CUDA/fvPpolot">CUDA</a></li>
<li><a href="/facts/Nvidia_RTX/KFEpm6lb">Nvidia RTX</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://developer.nvidia.com/optix">NVIDIA OptiX Application Acceleration Engine main page</a></li>
<li><a href="https://raytracing-docs.nvidia.com/">OptiX Programming Guide and OptiX SDK</a></li>
<li><a href="https://devtalk.nvidia.com/default/board/254/optix/">OptiX support Forum</a></li>
<li><a href="https://gitlab.com/ingowald/optix7course">OptiX 7 Course Tutorial Code</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"Scheduling in OptiX, the Nvidia ray tracing engine" (PDF). August 15, 2009. <a href="http://highperformancegraphics.org/previous/www_2009/presentations/nvidia-rt.pdf" target="_blank">http://highperformancegraphics.org/previous/www_2009/presentations/nvidia-rt.pdf</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Felbecker, Robert; Raschkowski, Leszek; Keusgen, Wilhelm; Peter, Michael (2012). "Electromagnetic wave propagation in the millimeter wave band using the NVIDIA OptiX GPU ray tracing engine". 2012 6th European Conference on Antennas and Propagation (EUCAP). IEEE Xplore. pp. 488–492. doi:10.1109/EuCAP.2012.6206198. ISBN 978-1-4577-0920-3. S2CID 45563615. <a href="978-1-4577-0920-3" target="_blank">978-1-4577-0920-3</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Steven G. Parker; Heiko Friedrich; David Luebke; Keith Morley; James Bigler; Jared Hoberock; David McAllister; Austin Robison; Andreas Dietrich; Greg Humphreys; Morgan McGuire; Martin Stich (2013). "Magazine Communications of the ACM - GPU ray tracing". Communications of the ACM. 56 (5). ACM: 93–101. doi:10.1145/2447976.2447997. S2CID 17174671. Retrieved August 14, 2013. <a href="https://dl.acm.org/citation.cfm?id=2447976.2447997" target="_blank">https://dl.acm.org/citation.cfm?id=2447976.2447997</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Steven G. Parker; James Bigler; Andreas Dietrich; Heiko Friedrich; Jared Hoberock; David Luebke; David McAllister; Morgan McGuire; Keith Morely; Austin Robison; Martin Stich (2010). "OptiX: a general purpose ray tracing engine". ACM Transactions on Graphics. 29 (4). ACM: 66:1–66:13. doi:10.1145/1778765.1778803. Retrieved August 14, 2013. <a href="https://dl.acm.org/citation.cfm?id=1778803" target="_blank">https://dl.acm.org/citation.cfm?id=1778803</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>"Blender 2.81 Benchmarks On 19 NVIDIA Graphics Cards - RTX OptiX Rendering Performance Is Incredible". phoronix.com. 2019. Retrieved November 26, 2019. <a href="https://www.phoronix.com/scan.php?page=article&item=blender-281-optix&num=1" target="_blank">https://www.phoronix.com/scan.php?page=article&item=blender-281-optix&num=1</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>"D-NOISE: Rapid AI Denoising for Blender". Remington Creative. July 20, 2019. Retrieved December 14, 2019. <a href="https://remington.pro/software/blender/d-noise/" target="_blank">https://remington.pro/software/blender/d-noise/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>"Adobe showcasing OptiX in a technology demo for ray tracing motion graphics with GPUs". NVIDIA. 2013. Archived from the original on December 20, 2021. Retrieved August 14, 2013. <a href="https://www.youtube.com/watch?v=3IwgBYBXPOA" target="_blank">https://www.youtube.com/watch?v=3IwgBYBXPOA</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>"Nvidia announces Gameworks Program at Montreal 2013; supports SteamOS". NVIDIA. 2013. Archived from the original on November 1, 2013. Retrieved October 29, 2013. <a href="https://web.archive.org/web/20131101065219/http://gearnuke.com/nvidia-announces-gameworks-program-montreal-2013-supports-steamos/" target="_blank">https://web.archive.org/web/20131101065219/http://gearnuke.com/nvidia-announces-gameworks-program-montreal-2013-supports-steamos/</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>"GPU changes (for CUDA and OpenGL) in After Effects CC (12.1) | After Effects region of interest". Retrieved February 22, 2015. <a href="https://blogs.adobe.com/creativecloud/gpu-changes-for-cuda-and-opengl-in-after-effects-cc-12-1/?segment=dva" target="_blank">https://blogs.adobe.com/creativecloud/gpu-changes-for-cuda-and-opengl-in-after-effects-cc-12-1/?segment=dva</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
<li id="fn:10"><p>"Daz Studio Changelog". DAZ 3D. Retrieved December 14, 2019. <a href="http://docs.daz3d.com/doku.php/public/software/dazstudio/4/change_log" target="_blank">http://docs.daz3d.com/doku.php/public/software/dazstudio/4/change_log</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li>
<li id="fn:11"><p>"New Features in v2.5 – LuxCoreRender". <a href="https://luxcorerender.org/new-features-in-v2-5/" target="_blank">https://luxcorerender.org/new-features-in-v2-5/</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li>
</ol>

OptiX open-in-new

OptiX