Priori map assisted indoor positioning method based on monocular camera

The invention provides a priori map assisted indoor positioning method based on a monocular camera. The method comprises the following steps: S1, acquiring a priori point cloud map of a closed-loop-free indoor scene; s2, performing semantic segmentation on a known priori map, extracting local point clouds with environment semantic information, and forming a simplified semantic line feature positioning map; and S3, extracting two-dimensional line features from the camera image, adding a semantic detection process, and adding a semantic tag to the two-dimensional line. S4, for a single-frame image, judging the visibility of line segments in the semantic positioning map, and matching two-dimensional line features with three-dimensional line segments which are in a view range and have consistent semantic tags; s5, constructing an optimization model matched with a prior map in real time, and improving the positioning precision of the system; the method solves the problem that it is difficult to depend on a closed-