Building change detection method based on density of projection points of movable window

The invention discloses a building change detection method based on the density of projection points of a movable window. The method comprises the steps that two periods of point cloud data are collected and registered; dimension-reducing analysis is carried out on a fixed wall; projection points of a station point in a plane of the fixed wall are calculated, and a structural coordinate system is established; the two periods of point cloud data are transformed to the structural coordinate system; a k-means classification method is used to obtain a brick point cloud and a mortar point cloud; the mortar point cloud is projected to the direction Z and the direction Y; a fixed window length Lfix and a movable window length Lmove are defined, and point-cloud linear density change along the direction Z and the direction Y is calculated; horizontal and vertical segmentation lines among bricks are calculated, coordinates of four corners of each brick and the center of each brick are calculated; and change is detected by utilizing the centers of the corresponding brick in two periods. According to the invention, deformation information of the centers of the bricks of the wall is extracted automatically, the automation degree is improved greatly, original data is mined fully, and it is ensured that deformation information of the bricks of a brick-structured building can be obtained effectively on the premise that the precision is ensured.