1 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Generic Graphics Architecture Radek Ošlejšek, Jiří Sochor Human Computer Interaction Laboratory Masaryk University, Brno Czech Republic

2 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Analysis of rendering strategies could bring: u Unified view on rendering strategies –rendering techniques are highly variable (radiosity, ray-tracing, photon-mapping, image-based rendering,... ) u Reusability of graphics components –BRDFs, spatial data structures, interpolators,... u HW acceleration of common components –exploring (some) modules of existing graphics pipelines –development of a new HW architecture/module u Detection of bottlenecks and possible parallelism of the rendering process u Exploitation of design patterns principles and invention of graphics patterns Introduction

3 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno u D. W. Fellner ( ) –Minimal Ray Tracer (MRT) architecture –Focused on ray-tracing and classical polygon-based local illumination u P. Slusallek and H.-P. Seidel (1995) –Vision architecture –cooperating subsystems u J. Döllner and K. Hinrichs (2002) –extensible scene graph structure using GoF design patterns –architecture over existing proprietary applications (OpenGL, POV-ray, RenderMan …) which are treated by the system of handles Previous Work

4 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Scene decomposition with properties u Extensibility - new objects, material descriptions, etc. u Efficiency - various spatial data structures Architectural view u Scene graph = container of virtual objects u Access through specialized Explorers –abstract interface for scene graph traversal –each explorer implements specific searching strategy (candidates for ray intersection, objects from given area …) Scene Graph

5 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno x' x x'' bi-directional reflection distribution function Rendering Equation geometry term / attenuation visibility emitted energy

6 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno x’ I(x') point / spot light Local Illumination

7 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno x’ loc I (x,x') rt I (x',x'') rt I (x',x'') local contributionRay-tracing

8 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno x' x'' not used (omnidirectional distribution) polygon centroidsRadiosity

9 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno PhongReflection setGlobalAmbient PhongBRDF PathTracing ProgRadiosity ReflectionModel illuminatePoint Radiosity RayTracing LocalReflection Reflection Model – Class Hierarchy Explorer BRDF Emittance

10 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno u Some reflection models require the deposition of non- uniform energy on object surfaces for later usage (radiosity, photon-tracing,... ) u Memory of integration u Coat descriptions: –Polygonal = surface discretized by fixed areas (polygons), colors associated with entire polygons or their vertices –2D map = 2D energy mapped on arbitrary 3D surface (texture, shadow map, impostor, etc.) –3D map = 3D description of energy (3D texture, photon map, etc.) Energy Coat

11 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Geometry EnergyCoat <<instantiate>> Mesh PolygonalEnergy setPolygonEnergy getPolygonEnergy setVertexEnergy getVertexEnergy EnergyMap setPointEnergy getPointEnergy ShadowMapImpostor Lumigraph Energy Coat - Class Hierarchy

12 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Covers the whole process of energy distribution –computes global energy by evaluation of reflection model –deposits precomputed energy in the form of energy coats –determines color of arbitrary point on surface either “on the fly” (e.g. ray-tracing) or by inspection of energy coat (e.g. final color interpolation in radiosity) Shading

13 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Shader distributeEnergy illuminatePoint GouraudShaderPhongShaderComboShader RTShaderProgRadShader LocalShaderGlobalShader Shading - Class Hierarchy ReflectionModel EnergyCoat instantiates

14 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno illuminatePoint visibleObjects objsOfInterest distributeEnergy rasterize renderScene distributeEnergy Explorer Scene Shader RendererFrameBuffer Rendering system Generic Rendering System

15 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno AABBs 14-DOPs Bounding spheres Original scene Testbed Library – Spatial Data Structures

16 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Cook-Torrance BRDF Blinn-Lambertian BRDF Lambertian BRDF Phong-Lambertian BRDF Testbed Library – Materials

17 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Flat shading Wire-frame model Smooth shading Ray-tracing Testbed Library – Rendering Strategies

18 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Testbed Library – Efficiency Tests

19 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno u More complex rendering strategies, e.g. photon mapping u Tricky algorithms not based on physical energy distribution (e.g. image-based rendering) u Detection of bottlenecks u Detection of possible parallelism u Participating media (fog, smoke, etc.) u Various efficiency tests, comparisons with proprietary systems Future Work

20 TPCG’03, Birmingham, UK © R.Ošlejšek, J.Sochor, FI MU Brno Thank you for attention !