Variational optic flow on the Sony PlayStation 3 – accurate dense flow fields for real-time applications

Abstract

While modern variational methods for optic flow computation offer dense flow fields and highly accurate results, their computational complexity has prevented their use in many real-time applications. With cheap modern parallel hardware such as the Sony PlayStation 3 new possibilities arise. For a linear and a nonlinear variant of the popular combined local-global (CLG) method, we present specific algorithms that are tailored towards real-time performance. They are based on bidirectional full multigrid methods with a full approximation scheme (FAS) in the nonlinear setting. Their parallelisation on the Cell hardware uses a temporal instead of a spatial decomposition, and processes operations in a vector-based manner. Memory latencies are reduced by a locality-preserving cache management and optimised access patterns. With images of size 316×252 pixels, we obtain dense flow fields for up to 210 frames per second.