proposed a SIFT-like descriptor called the mean–standard deviation line descriptor (MSLD). Along with SIFT generation, gradient-based descriptors are becoming increasingly popular.

A similarity measure based directly on gray information is affected by light variation and the robustness of the descriptors is low.

constructed a color histogram as a local line descriptor and used a topological filter to remove incorrect candidates. achieved line matching by comparing the gray correlation of line neighborhood windows. A line descriptor is constructed to describe the local features of the line, and line matching is achieved by measuring the similarity between the line descriptors. The second type of approach is line matching based on a line descriptor. proposes a matching approach that is mainly based on the affine invariance of the line and points that are located around the line segment, which are assumed to be coplanar located with the line in 3D space. used the corresponding Delaunay triangulations, constructed by reliable corresponding points, to constrain the initial matching candidates, and the final line-to-line correspondence was determined by a gray correlation method based on adaptive moving windows. Among them, the most preferred constraint is probably the epipolar constraint, which can limit the matching candidates to a small quadrilateral region and is often used as a benchmark for determining the corresponding direction of two images. Here, the existing geometric constraints, such as epipolar constraint, triangulation constraint and line-point invariant constraint, are often used. Therefore, a combination of multiple constraints is mostly used in the line matching process.

Due to the uncertainty of the endpoints of lines and lines that are broken during line segment extraction, a line matching algorithm with a single geometric constraint matching is insufficient. The main geometric properties commonly used are length, overlapping, distance, gradient, etc. The first is line matching based on geometric properties.

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