Earthquake-induced building damage detection method based on normal computation of neighboring points searching on 2D-plane

Earthquake-induced building collapse is one of the main reason for casualties. Airborne Laser Scanning (ALS) can acquire high resolution three-dimensional point cloud data. It is possible to detect building damage use post-earthquake ALS point cloud data. Due to the height difference of buildings, earthquake-induced building collapse cannot detect by height change directly, especially in large area. This paper proposed a neighboring points searching method to calculate the normal vector of damage building roof point cloud data, then compute the angle between normal vector and zenith direction, α. Through calculate α of typical damage building, we found that the angle can be used to detect building damage. After test with the large area using this method and select local region to evaluate the result, the kappa value is 0.75 shows it is an effective method to detect building damage.