INTRODUCTION TO OPTIX Martin Stich, Engineering Manager OptiX - PowerPoint PPT Presentation

INTRODUCTION TO OPTIX Martin Stich, Engineering Manager

OptiX Basics Advanced Topics AGENDA Case Studies Feature Outlook 2

OPTIX BASICS 3

IN A NUTSHELL The OptiX Ray Tracing SDK State-of-the-art performance: 500M+ rays/sec Algorithm and hardware agnostic Shaders with single-ray programming model, recursion Available free for private and commercial use 4

RELEASE TIMELINE OptiX 3.9 OptiX 4.0 OptiX 4.1 OptiX 1.0 ... Pascal Support LLVM Pipeline Performance Hello World! NVLINK Scaling CUDA 8, VS2015 2009 Jan 2016 Summer 2016 TODAY! 5

MODERN RAY TRACING Rasterization: 6

MODERN RAY TRACING Rasterization: Ray Tracing: 7

THE RAY TRACING PIPELINE INTERSECTION ANY-HIT Programmable: INTERSECTION ANY-HIT Ray Generation ← Launch entry CLOSEST-HIT Closest Hit, Any Hit, Miss ← Shading Intersection ← Geometry RAY GENERATION 8

MAIN OPERATIONS RAY GEN INTERSECT ANY HIT CLOSEST HIT MISS ✔ ✔ ✔ rtTrace ✔ rtPotentialIntersection ✔ rtReportIntersection ✔ rtIgnoreIntersection ✔ rtTerminateRay 9

SHADER COMMUNICATION Variables Example: similar to uniforms in other systems Textures Current ray constants, system values, buffers, textures, … 10

SHADER COMMUNICATION Variables Example: similar to uniforms in other systems Textures Current ray constants, system values, buffers, textures, … Ray Payload arbitrary data associated with ray Example: Color data in/out from rtTrace to Any-hit, Closest-hit, Miss 11

SHADER COMMUNICATION Variables Example: similar to uniforms in other systems Textures Current ray constants, system values, buffers, textures, … Ray Payload arbitrary data associated with ray Example: Color data in/out from rtTrace to Any-hit, Closest-hit, Miss Attributes arbitrary data associated with hit Example: generated in Intersection program Barycentrics consumed by Any-hit, Closest-hit 12

EXAMPLE Miniature Path Tracer See optixPathTracer SDK sample for a slightly less minimalistic version 13

GLOBAL ILLUMINATION 14

GLOBAL ILLUMINATION 15

GLOBAL ILLUMINATION 16

GLOBAL ILLUMINATION 17

HOWEVER… 18

RAY PAYLOAD Path State Definition struct RayPayload { float3 radiance; // stores contribution after we hit the light source float3 attenuation; // accumulated attenuation of radiance due to materials float3 next_origin; // reflection ray to be traced for the next float3 next_direction; // ..segment of the path unsigned seed; // random number generator state bool done; // whether we’re done tracing this path }; 19

INTEGRATION RT_PROGRAM void ray_generation() { 1 unsigned int seed = tea<16>( launch_index.x + launch_index.y * output_buffer.size().x , frame_number ); float3 ray_origin = eye ; float3 ray_direction = compute_jittered_ray_dir( seed ); RayPayload payload; payload.radiance = make_float3(0,0,0); 2 payload.attenuation = make_float3(1,1,1); payload.seed = seed; payload.done = false; int depth = 0; while( !payload.done && depth++ < 10 ) { Ray ray = make_Ray( ray_origin, ray_direction, 0, 0.001f, RT_DEFAULT_MAX ); 3 rtTrace( scene, ray, payload ); ray_origin = payload.next_origin; ray_direction = payload.next_direction; } const float3 result = payload.radiance * payload.attenuation; 4 const float lerp_t = frame_number > 1 ? 1.0f / frame_number : 1.0f; const float3 prev_col = make_float3( output_buffer [ launch_index ] ); output_buffer [ launch_index ] = make_float4( lerp( prev_col, result, lerp_t ), 1.0f ); } 20

DIFFUSE MATERIAL rtDeclareVariable( float3, diffuse_color, , ); rtDeclareVariable( float3, normal, attribute normal, ); rtDeclareVariable( optix::Ray, ray, rtCurrentRay , ); rtDeclareVariable( float, t_hit, rtIntersectionDistance , ); rtDeclareVariable( RayPayload, current_payload, rtPayload , ); RT_PROGRAM void closest_hit_diffuse() { const float3 hitpoint = ray.origin + t_hit * ray.direction ; const float z1 = rnd( current_payload.seed ); const float z2 = rnd( current_payload.seed ); float3 dir; cosine_sample_hemisphere( z1, z2, dir ); optix::Onb onb( normal ); onb.inverse_transform( dir ); current_payload.next_origin = hitpoint; current_payload.next_direction = dir; current_payload.attenuation *= diffuse_color ; } 21

LIGHT MATERIAL AND MISS rtDeclareVariable( RayPayload, current_payload, rtPayload , ); rtDeclareVariable( float3, emission_color, , ); RT_PROGRAM void closest_hit_light() { current_payload.radiance = emission_color ; current_payload.done = true; } RT_PROGRAM void miss() { current_payload.radiance = make_float3(0,0,0); current_payload.done = true; } 22

SCENE GEOMETRY rtDeclareVariable( float3, anchor, , ); rtDeclareVariable( float3, v1, , ); rtDeclareVariable( float3, v2, , ); rtDeclareVariable( float4, plane, , ); rtDeclareVariable( float3, normal, attribute normal, ); rtDeclareVariable( optix::Ray, ray, rtCurrentRay , ); RT_PROGRAM void intersect( int primIdx ) { const float3 n = make_float3( plane ); const float dt = dot( ray.direction , n ); const float t = ( plane.w - dot(n, ray.origin )) / dt; const float3 p = ray.origin + ray.direction * t; const float3 vi = p - anchor ; const float a1 = dot( v1 , vi ); const float a2 = dot( v2 , vi ); if( a1 >= 0 && a1 <= 1 && a2 >= 0 && a2 <= 1 ) { if( rtPotentialIntersection( t ) ) { normal = n; rtReportIntersection( 0 ); } } } 23

RESULT Accumulation Over Time 24

NEXT STEP IDEAS Mini Path Tracer Reader Exercises Next event estimation Russian roulette Sphere primitives Mirror material Glass material Triangle meshes Environment maps ... 25

NODE GRAPH Context Group Geometry Group Geometry Variables Instance Intersection Geometry Program Any Hit + Material Closest Hit 26

ADVANCED TOPICS 27

INTEROP Share CUDA and OpenGL Resources OpenGL Share textures and vertex buffers rtBufferCreateFromGLBO rtTextureSamplerCreateFromGLImage CUDA Share CUDA allocations rtBufferSetDevicePointer rtBufferGetDevicePointer 28

BINDLESS OBJECTS “Bindless” : powerful concept to dynamically select textures, buffers, and programs at runtime Allows efficient implementation of large shading networks Reduces code size, compile times, and number of compiles Pixar Animation Studio’s “ Flow ” material editing tool. Visit the NVIDIA website to watch a SIGGRAPH 2015 talk describing the system in detail. 29

PTX GENERATION Options Offline CUDA-C++ nvcc.exe OptiX nvrtc.dll PTX CUDA-C++ JIT NVVM/ LLVM-IR NVPTX 30

MULTI-GPU AND NVLINK Automatic Scaling 110M Triangles 23M Grass Blades 15GB Textures 2 x GP100 31 Monsters University data set courtesy of Pixar Studios

REMOTE RENDERING On Quadro VCA or DGX-1 Incremental updates Progressive OptiX App video stream ETHERNET INTERNET OptiX Server(s) 32

OPTIX PRIME Simple intersection-only API Rays OptiX Prime Intersections (primIdx, t, u, v) GPU or CPU Triangles Supports instancing, async operations, ray masks Performance similar to OptiX Same semantics via OptiX: See optixRaycasting sample 33

CASE STUDIES 34

PERFORMANCE Raw Traversal on Titan X Pascal +3% in OptiX 4.1 +16% in OptiX 4.1 35

NVIDIA: IRAY & MENTAL RAY 36

NVIDIA: GVDB Sparse Volume Rendering OpenVDB format support Image Property of DreamWorks Animation Live interaction with multiple- bounce GI scattering, 10x-30x faster than CPU Introduction and Techniques with NVIDIA GVDB Voxels Monday, 9:00 AM – Room 231 37

AAA-STUDIO: FURRYBALL PRODUCTION RENDERING 38

VISUAL MOLECULAR DYNAMICS (VMD) Molecular Visualization package with hundreds of thousands of users Developed by John Stone of U Illinois Cutting Edge OptiX Ray Tracing Techniques for Visualization of Biomolecular and Cellular Simulations in VMD Tuesday, 3:30 PM – Room 230C 39

OLCF: SCIENTIFIC VISUALIZATION Visualizing laser interaction with metals, hundreds of millions of primitives on DGX-1 Developed by Benjamin Hernandez, OLCF-ORNL Exploratory Visualization of Petascale Particle Data in NVIDIA DGX-1 Tuesday, 3:30 PM – Room 212B Simulation: OLCF INCITE 2017 "Petascale Simulations of Short Pulse Laser Interaction with Metals" PI Leonid Zhigilei, University of Virginia 40

NVIDIA: VRWORKS AUDIO Sound waves reflect Path traced audio off of the environment NVIDIA VRWORKS AUDIO - Improving VR Immersion with acoustic fidelity Thursday, 11:00 AM – Room 230B 41

BUNGIE: LIGHT BAKING FOR GAMES Light and occlusion baking is a major bottleneck in game design Workflow-changing speedups by switching from CPU render farms to OptiX 42

LIGHTMASS Light baking in Unreal Engine 4 Total Time on Titan X CPU 1638s GPU 1X 426s GPU 2X 298s 43

ADVANCED SAMPLES Maintained on Github A collection of larger, more sophisticated sample applications than the ones that come with the SDK Available at: https://github.com/ nvpro-samples/optix_advanced_samples 44

FEATURE OUTLOOK 45