A constraints-based approach using ranking-gradient-similarity multi-block matching algorithm.

Many works have been done in stereo vision due to its critical importance to the different uses and various areas of computer vision. Recently, the popularity of research on the local block matching algorithm is difficult to compete with the convolutional neural network (CNN) approach, whereby the latter method can achieve higher accuracy at the expense of time consumption. However, the simplicity of the local block matching algorithm is easier to be implemented in real applications at a lower cost. Therefore, this paper presents a new study that improved computation and cost aggregation using a progressive approach. A new algorithm to aid in searching locally similar blocks called the ranking-gradient-similarity multi-block strategy (RGSMB) has been presented, improving processing time and accuracy. A new cost computation has been introduced in the proposed algorithm, which fully utilises the information from the limited local window region by combining the cost from three different constraints, including a Ranking constraint, a Gradient constraint, and a Similarity constraint. The proposed algorithm can accomplish remarkable accuracy by combining with multi-block matching (MBM), which is developed to diminish the conventional cost aggregation's constrained shape limitation. We evaluate the RGSMB algorithm's performance and other CNN methods for comparison. KITTI 2012 dataset of 194 and 195 image pairs and the KITTI 2015 dataset of 200 image pairs were used for training and testing. The results indicate that the proposed algorithm is better than the existing approaches, with a higher matching rate using the KITTI benchmark dataset. Compared to existing local block matching algorithms, the average errors of the RGS are less than the CT approach by nearly 9%, which is the 2nd ranked in this analysis. Also, the RGSMB has average errors of 21% less than the S 7 + correlation when comparing with existing CNN methods. It was also observed that the RGSMB could estimate the disparity value more accurately in the depth discontinuities and homogenous regions. [ABSTRACT FROM AUTHOR]