Dynamic Upsampling of Smoke through Dictionary-based Learning

Kai Bai*¹, Wei Li*¹, Mathieu Desbrun², Xiaopei Liu¹

ACM Transactions on Graphics, accepted for publication, 2020

1. ShanghaiTech University
2. California Institute of Technology
 

Abstract

Simulating turbulent smoke flows with fine details is computationally intensive. For iterative editing or simply faster generation, efficiently upsampling a low-resolution numerical simulation is an attractive alternative. We propose a novel learning approach to the dynamic upsampling of smoke flows based on a training set of flows at coarse and fine resolutions.Our multiscale neural network turns an input coarse animation into a sparse linear combination of small velocity patches present in a precomputed over-complete dictionary. These sparse coefficients are then used to generate a high-resolution smoke animation sequence by blending the fine counterparts of the coarse patches. Our network is initially trained from a sequence of example simulations to both construct the dictionary of corresponding coarse and fine patches and allow for the fast evaluation of a sparse patch encoding of any coarse input. The resulting network provides an accurate upsampling when the coarse input simulation is well approximated by patches present in the training set (e.g., for re-simulation), or simply visually-plausible upsampling when input and training set differ significantly. We show a variety of examples to ascertain the strengths and limitations of our approach, and offer comparisons to existing approaches to demonstrate its quality and effectiveness.

     
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