Patch-based texture synthesis on 3D fluids

Abstract

We propose three different approaches to synthesise a texture on an animated fluid free surface based on texture exemplars. Overall, our approaches are applied as a post-process to a fluid simulation. We used polygon patches to store texture uv coordinates. We advect trackers or polygon patches to move the texture along the fluid flow. The patches are covering the whole surface every frame of the animation. We use a texture atlas to compute the resulting animated texture. In the first approach, particle trackers are scattered on the surface of the fluid, and used to track deformations and topological changes. For every frame of the animation, the trackers are advected and rotated coherently with the flow of the fluid. Receiver polygons are identified on the fluid surface and are used to transfer uv coordinates, while ensuring a controllable amount of texture distortion. The density of the trackers is adjusted when constructing a texture atlas used for rendering. Trackers that remain unused when filling the atlas are safely removed, while texels of the atlas without any corresponding tracker identify areas where new trackers will be added. Together with our patch layering approach, this tracker creation and removal process reduces popping artifacts. In the second approach, we synthesize temporally coherent patch-based textures on the free surface of fluids using deformable patches. We seek to maintain a Poisson disk distribution of patches, and following advection, the Poisson disk criterion determines where to add new patches and which patches should be flagged for removal. The removal considers the local number of patches: in regions containing too many patches, we accelerate the temporal removal. This reduces the number of patches while still meeting the Poisson disk criterion. Reducing areas with too many patches speeds up the computation and avoids patch-blending artifacts. In the third approach, using lapped textures combined with deformable patches, we successfully remove blending artifact and rigid artifact seen in previous methods. We remain faithful to the texture exemplar by removing distorted patch texels using a patch erosion process. The patch erosion is based on a feature map provided together with the exemplar as inputs to our approach. The erosion favors removing texels toward the boundary of the patch as well as texels corresponding to more distorted regions of the patch. Where texels are removed leaving a gap on the surface, we add new patches below existing ones. The result is an animated texture following the velocity field of the fluid. We show that our approaches provide good results for many fluid simulation scenarios, and with many texture exemplars.

Date	5 Aug 2022
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Eric Paquette (Supervisor)