Windows and Doors Extraction from Point Cloud Data Combining Semantic Features and Material Characteristics

Point cloud data have become the primary spatial data source for the 3D reconstruction of building engineering, where 3D reconstructed building information models can improve construction efficiency. In such applications, detecting windows and doors is essential. Previous research mainly used red-green-blue (RGB) information or semantic features for detection, where the combination of these two features was not considered. Therefore, this research proposed a practical approach to detecting windows and doors using point cloud data with the combination of semantic features and material characteristics. The point cloud data are first segmented using Gradient Filtering and Random Sample Consensus (RANSAC) to obtain the 3D indoor data without intrusions and protrusions. As input, the 3D indoor data are projected to horizontal planes as 2D point cloud data. The 2D point cloud data are then transformed to 2D images, representing the indoor area for feature extraction. On the 2D images, the 2D boundary of each potential opening is extracted using an improved Bounding Box algorithm, and the extraction result is transformed back to 3D data. Based on the 3D data, the reflectivity of building material is applied to differentiate windows and doors from potential openings, and the number of data points is used to check the opening condition of windows and doors. The abovementioned approach was tested using the point cloud data representing one campus building, including two big rooms and one corridor. The experimental results showed that accurate detection of windows and doors was successfully reached. The completeness of the detection is 100%, and the correctness of the detection is 90.32%. The total time for the feature extraction is 22.8 s for processing 2 million point cloud data, including time from reading data of 10.319 s and time from showing the results of 4.938 s.