随着经济的发展，城市化进程不断加快，城市处于不断的变化之中。准确的提取

With economic development, urbanization continues to accelerate, the city is in constant change. Accurate extraction of surface change information is an important basis for the analysis of urbanization, the level of urban economic development, urban population distribution and urban districts function. The traditional method of surface monitoring, requires a lot of manpower and material resources and time, high cost, long time. Optical remote sensing technology that is easily affected by weather conditions, at night, cloudy, rain, snow and other weather conditions can not be clearly observed by ground objects.

With the development of economy, the process of urbanization is accelerating, and the city is in constant change. Accurate extraction of surface change information is an important basis for analyzing the process of urbanization, the level of urban economic development, the distribution of urban population and the function of urban districts. The traditional surface monitoring method requires a lot of manpower and material resources and time, the cost is high and the time is long. Optical remote sensing technology is highly susceptible to weather conditions, in the dark, cloudy, rain and snow and other weather conditions, it is not clear lying to observe the object of the earth.

With the development of economy, the process of urbanization is accelerating, and the city is in constant change. Accurate extraction of surface change information is an important basis for analyzing urbanization process, urban economic development level, urban population distribution and urban functions. The traditional surface monitoring method needs a lot of manpower and material resources and time, with high cost and long time. Optical remote sensing technology is very vulnerable to weather conditions, in the dark, cloudy, rain and snow and other weather conditions, it can not clearly observe the ground objects.