Pixar

Alexis Angelidis

Philip Child

Jacob Porter Merrell

Robert Moyer

Danny Nahimias

Bill Watral

Gary Bruins

A multi-scale method is provided for computer graphic simulation of incompressible gases in three-dimensions with resolution variation suitable for perspective cameras and regions of importance. The dynamics is derived from the vorticity equation. Lagrangian particles are created, modified and deleted in a manner that handles advection with buoyancy and viscosity. Boundaries and deformable object collisions are modeled with the source and doublet panel method. The acceleration structure is based on the fast multipole method (FMM), but with a varying size to account for non-uniform sampling.

Computer graphic system and method of multi-scale simulation of smoke

Particular embodiments comprise providing a surface mesh for an object, generating a voxel grid comprising volumetric masks for the mesh, and generating a lit mesh, wherein the lit mesh comprises a shaded version of the mesh as positioned in a scene. The voxel grid may be positioned over the lit mesh in the scene, and a first ray may be traced to a position of the voxel grid. If the traced ray passed through the voxel grid and hit a location on the lit mesh, then one or more second rays may be traced to the hit location on the lit mesh. If the traced ray hit a location in the voxel grid but did not hit a location on the lit mesh, then one or more second rays may be traced from the hit location in the voxel grid to the closest locations on the lit mesh. Finally, color sampled at one or more locations proximate to the position of the voxel grid may be blurred outward through the voxel grid to create a volumetric projection.

Generating a volumetric projection for an object

The disclosure provides an approach for animating gases. A dynamic model is employed that accounts for stretching of gas vorticles in a stable manner, handles isolated particles and buoyancy, permits deformable boundaries of objects the gas flows past, and accounts for vortex shedding. The model models stretching of vorticity by applying a vector at the center of a stretched vorticle. High frequency eddies resulting from stretching may be filtered by unstretching the vorticle while preserving mean energy and enstrophy. To model boundary pressure, a boundary may be imposed by embedding into the gas the surface boundary and setting boundary conditions based on velocity of the boundary and the Green's function of the Laplacian. For computational efficiency, a vorticle cutoff proportional to a vorticle's size may be imposed. Vorticles determined to be similar based on a predefined criteria and distance threshold may be fused.

Method and system for vorticle fluid simulation

Techniques for determining a shading rate of a volumetric element in a rendered scene when the rendered scene is viewed from a first point of view are provided. Embodiments determine a viewable area of the volumetric element, as viewed from the first point of view. A shading rate to use in processing the volumetric element is then determined, based on the determined viewable area. Embodiments processing the volumetric element at the determined shading rate using one or more shaders.

Efficient rendering of volumetric elements

A wave modeler usable with a rendering engine and for generating surface models usable for rendering images of scenes having surfaces therein reads user inputs including a desired displacement value, determines a vertical displacement wave representing displacements along a wave, determines a plurality of sample points each having an ordinal position on the vertical displacement wave, determines a horizontal displacement wave, maps the horizontal displacement wave to the plurality of sample points, adjusts horizontal displacement of one or more of the plurality of sample points to prevent, avoid or reduce intersection of the wave with itself, and generates a representation of the wave that is storable as a geometric model usable by a rendering image to generate an image with corresponding displacements of the wave.

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Albany, CA, United States of America

Alexis Angelidis