CNLPA-MVS: Coarse-Hypotheses Guided Non-Local PatchMatch Multi-View Stereo

In multi-view stereo, unreliable matching in low-textured regions has a negative impact on the completeness of reconstructed models. Since the photometric consistency of low-textured regions is not discriminative under a local window, non-local information provided by the Markov Random Field (MRF) model can alleviate the matching ambiguity but is limited in continuous space with high computational complexity. Owing to its sampling and propagation strategy, PatchMatch multi-view stereo methods have advantages in terms of optimizing the continuous labeling problem. In this paper, we propose a novel method to address this problem, namely the Coarse-Hypotheses Guided Non-Local PatchMatch Multi-View Stereo (CNLPA-MVS), which takes the advantages of both MRF-based non-local methods and PatchMatch multi-view stereo and compensates for their defects mutually. First, we combine dynamic programing (DP) and sequential propagation along scanlines in parallel to perform CNLPA-MVS, thereby obtaining the optimal depth and normal hypotheses. Second, we introduce coarse inference within a universal window provided by winner-takes-all to eliminate the stripe artifacts caused by DP and improve completeness. Third, we add a local consistency strategy based on the hypotheses of similar color pixels sharing approximate values into CNLPA-MVS for further improving completeness. CNLPA-MVS was validated on public benchmarks and achieved state-of-the-art performance with high completeness.