Discussion on the automatic extraction of urban area´s variation info from TM image

The extraction of urban area´s variation info from remote sensing image is an important step for monitoring and measuring urban change. In this paper, a structural method will construct for automatically extracting variation information of urban area. The methodology is constructed by L-Ratio method which is base on PCA, method of digital image processing (threshold value, mask layer and so on) and opening of mathematical morphology. It acquired a good experimental effect.