Parameterized Cost Volume for Stereo Matching.

Stereo matching becomes computationally challenging when dealing with a large disparity range. Prior methods mainly alleviate the computation through dynamic cost volume by focusing on a local disparity space, but it requires many iterations to get close to the ground truth due to the lack of a global view. We find that the dynamic cost volume approximately encodes the disparity space as a single Gaussian distribution with a fixed and small variance at each iteration, which results in an inadequate global view over disparity space and a small update step at every iteration. In this paper, we propose a parameterized cost volume to encode the entire disparity space using multi-Gaussian distribution. The disparity distribution of each pixel is parameterized by weights, means, and variances. The means and variances are used to sample disparity candidates for cost computation, while the weights and means are used to calculate the disparity output. The above parameters are computed through a JS-divergence-based optimization, which is realized as a gradient descent update in a feed-forward differential module. Experiments show that our method speeds up the runtime of RAFT-Stereo by 4 ~ 15 times, achieving real-time performance and comparable accuracy. The code is available at https://github.com/jiaxiZeng/Parameterized-Cost-Volume-for-Stereo-Matching.