The “Fuzzy” Repair of Urban Building Facade Point Cloud Based on Distribution Regularity

Abstract

The integrity of point cloud is the basis for smoothly ensuring subsequent data processing and application. For “Smart City” and “Scan to Building Information Modeling (BIM)”, complete point cloud data is essential. At present, the most commonly used methods for repairing point cloud holes are multi-source data fusion and interpolation. However, these methods either make it difficult to obtain data, or they are ineffective at repairs or labor-intensive. To solve these problems, we proposed a point cloud “fuzzy” repair algorithm based on the distribution regularity of buildings, aiming at the façade of a building in an urban scene, especially for the vehicle Lidar point cloud. First, the point cloud was rotated to be parallel to the plane XOZ, and the feature boundaries of buildings were extracted. These boundaries were further classified as horizontal or vertical. Then, the distance between boundaries was calculated according to the Euclidean distance, and the points were divided into grids based on this distance. Finally, the holes in the grid that needed to be repaired were filled from four adjacent grids by the “copy–paste” method, and the final hole repairs were realized by point cloud smoothing. The quantitative results showed that data integrity improved after the repair and conformed to the state of the building. The angle and position deviation of the repaired grid were less than 0.54° and 3.25 cm, respectively. Compared with human–computer interaction and other methods, our method required less human intervention, and it had high efficiency. This is of promotional significance for the repair and modeling of point cloud in urban buildings.