Efficient dense reconstruction of objects or scenes has substantial practical implications, which can be applied to different 3D tasks (for example, robotics and autonomous driving). However, because of the expensive hardware required and the overall complexity of the all-around scenarios, efficient dense reconstruction using lightweight multi-view stereo methods has received much attention from researchers. The technological challenge of efficient dense reconstruction is maintaining low memory usage while rapidly and reliably acquiring depth maps. Most of the current efficient multi-view stereo (MVS) methods perform poorly in efficient dense reconstruction, this poor performance is mainly due to weak generalization performance and unrefined object edges in the depth maps. To this end, we propose EMO-MVS, which aims to accomplish multi-view stereo tasks with high efficiency, which means low-memory consumption, high accuracy, and excellent generalization performance. In detail, we first propose an iterative variable optimizer to accurately estimate depth changes. Then, we design a multi-level absorption unit that expands the receptive field, which efficiently generates an initial depth map. In addition, we propose an error-aware enhancement module, enhancing the initial depth map by optimizing the projection error between multiple views. We have conducted extensive experiments on challenging datasets Tanks and Temples and DTU, and also performed a complete visualization comparison on the BlenedMVS validation set (which contains many aerial scene images), achieving promising performance on all datasets. Among the lightweight MVS methods with low-memory consumption and fast inference speed, our F-score on the online Tanks and Temples intermediate benchmark is the highest, which shows that we have the best competitiveness in terms of balancing the performance and computational cost.

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Stereo matching is the process of establishing correspondence between different perspective images of the same scene. A global optimal method that can deliver a dense disparity m a p is preferable t o a method producing sparse displacement results or a method based o n local optimization. W e present a n eflective global optimized stereo matching approach that produces a dense displacement m a p and a n occlusion map. T h e global matching cost and various constraints, including matching uniqueness and ordering, and local smoothness along and across epipolar lines, are all cast into a novelly configured m a x i m u m flow graph. T h e correspondence between the associated minimum cut and the defined stereo problem guarantees a global optimized disparity solution confined by those geometric constraints while still preserving discontinuities: Test results show the eficacy of the algorithm.

It is well known that preserving depth edges is an effective solution for achieving the accurate disparity map in stereo matching, but many state-of-the-art methods do not preserve depth edges well. In order to solve it efficiently, the cell structure containing irregular and regular shape regions is designed to preserve depth edges. Based on the well-designed cell structure, a novel disparity estimation method for stereo matching is proposed, in which a two-layer disparity optimization method is proposed to refine the disparity plane; it includes the front-parallel disparities computation and slanted-surfaces disparity plane refinement. In the framework of front-parallel disparities computation, a tree-based cost aggregation method is presented to make full use of the segmentation information of cells and then performing semi-global cost aggregation. In the framework of slanted-surfaces disparity plane refinement, a new probability model is proposed that employs Bayesian inference for refining disparities in textureless, weak texture and occluded regions. Experimental results show that higher accuracy could be achieved via the proposed method compared with some known state-of-the-art stereo methods on KITTI 2015 and Middlebury dataset, which are the standard benchmarks for testing the stereo matching methods. It can also be indicated that the proposed method can produce accurate disparity map and have good generalization performance.

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