A Hardware Accelerator for the Semi-Global Matching Stereo Algorithm: An Efficient Implementation for the Stratix V and Zynq UltraScale plus FPGA Technology

The semi-global matching stereo algorithm is a top performing algorithm in stereo vision. The recursive nature of the computations involved in this algorithm introduces an inherent data dependency problem, hindering the progressive computations of disparities at pixel clock. In this work, a novel hardware implementation of the semi-global matching algorithm is presented. A hardware structure of parallel comparators is proposed for the fast computation of the minima among large cost arrays in one clock cycle. Also, a hardware-friendly algorithm is proposed for the computation of the minima among far-indexed disparity costs, shortening the length of computations in the datapath. As a result, the recursive path cost computation is accelerated considerably. The system is implemented in a Stratix V device and in a Zynq UltraScale+ device. A throughput of 55,1 million disparities per second is achieved with maximum disparity 128 pixels and frame resolution 1280 x 720. The proposed architecture is less elaborate and more resource efficient than other systems in the literature and its performance compares favorably to them. An implementation on an actual FPGA board is also presented and serves as a real-world verification of the proposed system.