Building Change Detection using Multi-Temporal Airborne LiDAR Data
This addresses urban monitoring and planning needs by automating building change detection from LiDAR data, but it is incremental as it builds on existing deep learning and segmentation techniques.
The study tackled building change detection from multi-temporal airborne LiDAR data by proposing an automatic method that reduces 3D point clouds into a smaller representation using a U-Net model for segmentation and morphological refinement, achieving classification into four change types (newly built, demolished, taller, shorter) with results visualized on a map.
Building change detection is essential for monitoring urbanization, disaster assessment, urban planning and frequently updating the maps. 3D structure information from airborne light detection and ranging (LiDAR) is very effective for detecting urban changes. But the 3D point cloud from airborne LiDAR(ALS) holds an enormous amount of unordered and irregularly sparse information. Handling such data is tricky and consumes large memory for processing. Most of this information is not necessary when we are looking for a particular type of urban change. In this study, we propose an automatic method that reduces the 3D point clouds into a much smaller representation without losing the necessary information required for detecting Building changes. The method utilizes the Deep Learning(DL) model U-Net for segmenting the buildings from the background. Produced segmentation maps are then processed further for detecting changes and the results are refined using morphological methods. For the change detection task, we used multi-temporal airborne LiDAR data. The data is acquired over Stockholm in the years 2017 and 2019. The changes in buildings are classified into four types: 'newly built', 'demolished', 'taller' and 'shorter'. The detected changes are visualized in one map for better interpretation.