Parallel Variational Motion Estimation by Domain Decomposition and Cluster Computing

We present an approach to parallel variational optical flow computation on standard hardware by domain decomposition. Using an arbitrary partition of the image plane into rectangular subdomains, the global solution to the variational approach is obtained by iteratively combining local solutions which can be efficiently computed in parallel by separate multi-grid iterations for each subdomain. The approach is particularly suited for implementations on PC-clusters because inter-process communication between subdomains (i.e. processors) is minimized by restricting the exchange of data to a lower-dimensional interface. By applying a dedicated interface preconditioner, the necessary number of iterations between subdomains to achieve a fixed error is bounded independently of the number of subdomains. Our approach provides a major step towards real-time 2D image processing using off-the-shelf PC-hardware and facilitates the efficient application of variational approaches to large-scale image processing problems.