An Image Analysis and Photogrammetric Engineering Integrated Shadow Detection Model

A model of automatically detecting the building shadows in high resolution aerial remote sensing image is introduced in this paper. The space coordinates of the shadows are first computed using photogrammetric engineering. To do this, digital surface model (DSM) and the sun zenith and azimuth angles are used. By camera model, the scanning line and the camera position are calculated for each space shadow. A contour driven height field ray tracing is proposed to determine the visibility of a shadow. For a visible shadow, its projecting in the image, called measured shadow, is calculated by collinearity equations. Then by image analysis the reference segmentation threshold is obtained from the intensity distribution of the measured shadows. At last, the image segmentation is implemented to get the precise image shadow areas.