Retrospect Digital Image Synthesis Yu-Ting Wu

So far we have learned: Geometry and transforms Shapes Accelerators Color and radiometry Cameras Sampling and reconstruction Reflection models Materials Textures

Recap: the process of rendering Cameras orthogonal, perspective, environment, realistic … Sampling random, stratified, low-discrepancy, best candidate … Reconstruction box, triangle, sinc, Gaussian, Mitchell … GenerateRay Intersect Shapes sphere, disk, cylinder, triangle meshes, subdivision surfaces … Intersection DifferentialGeometry BSDFs Materials matte, plastic, mix, measured, metal, substrate … Lights point, distant, spot, area, environment … Accelerators grid, bvh, kdtree … GetBSDF

Cameras GenerateRay –Given a sample on the image film (in raster space), generate the corresponding camera ray (in world space) according to the type of camera. environment

Cameras Depth-of-field and motion blur Depth-of-field Motion blur

Shapes Intersect (used for radiance ray) Given a ray, does it has intersection with the shape? If yes, fill the information in DifferentialGeometry IntersectP (used for shadow ray) –Given a ray, does it has intersection with the shape? Intersect IntersectP scene

Materials, textures and reflectance models Materials –GetBSDF Reflectance models (BxDFs) –f –Sample_f Textures –Evaluate Material Texture Spatially-varying parameters BxDFs reflectance models

Accelerators Construction Traversal Intersect (used for radiance ray) –IntersectP (used for shadow ray) BVH Uniform grid OctreeKdtreeBSP tree

Sampling and reconstruction Use sub-pixel samples for –Antialiasing –Distributed effects Depth-of-field Motion blur Soft shadows Glossy reflection Global illumination

Sampling and reconstruction Sampling patterns random stratified uniform stratified jittered HaltonHammersleybest candidate

Call stack in pbrt Renderer::Render RenderTask::Run Camera::Film::WriteImage RenderTask::Run Camera::GenerateRay Renderer::Li Scene::Intersect if there is an intersection SurfaceIntegrator::Li else Light::Le VolumeIntegrator::Li return T * Li + Lvi [render a block of pixels] [output an image] [obtain a camera ray for each camera sample] [compute the radiance carried by the camera ray] [obtain the intersection of the ray and the scene] [compute the surface reflectance along the ray] [possibly add emittance from all lights] [compute volume contribution and transmittance]

Call stack in pbrt Scene::Intersect Aggregate::Intersect SurfaceIntegrator::Li Intersection::GetBSDF Intersection::GetBSDF Primitive::GetBSDF Shape::GetShadingGeometry Material::GetBSDF [call acceleration structure for intersection] [get BSDF for shading] [call the intersected primitive to fill the BSDF ] [call shape to get shading geometry] [do bump mapping if necessary, call material to get BSDF]

Remaining components: Lights Monte Carlo Surface integrators Volume integrators

Recap: the process of rendering Cameras orthogonal, perspective, environment, realistic … Sampling random, stratified, low-discrepancy, best candidate … Reconstruction box, triangle, sinc, Gaussian, Mitchell … GenerateRay Intersect Shapes sphere, disk, cylinder, triangle meshes, subdivision surfaces … Intersection DifferentialGeometry BSDFs Materials matte, plastic, mix, measured, metal, substrate … Lights point, distant, spot, area, environment … Accelerators grid, bvh, kdtree … Li How much radiance reflected from surface?  Surface Integrators GetBSDF

Recap: the process of rendering Cameras orthogonal, perspective, environment, realistic … Sampling random, stratified, low-discrepancy, best candidate … Reconstruction box, triangle, sinc, Gaussian, Mitchell … GenerateRay Intersect Accelerators grid, bvh, kdtree … Shapes sphere, disk, cylinder, triangle meshes, subdivision surfaces … How much radiance absorbed and scattered by the media?  Volume Integrators Intersection DifferentialGeometry BSDFs Materials matte, plastic, mix, measured, metal, substrate … Lights point, distant, spot, area, environment … GetBSDF

Recap: the process of rendering Are we close to this beautiful image?

What’s for next? Lights Homework assignment #3 A brief introduction to the Many-Light rendering