The Research For The Application Of 3S Integrate Technology To Land Change Survey

Land is the base for the living and developing of human, and also is the basic element for the building of a country. It is the basic situation of our country that it has so many people and so mouthful land for per people. It is very significant to survey the situation of our land and give the scientific evaluation.It took 20 years to survey the situation of our country. Today, with the developing of science and technology, it cannot fulfill the requirement for land changing survey using traditional method. The developing of 3S brings the light. 3S is to be integrated using PDA, making use of the map of RS/GIS as the map for survey, putting use of the positioning function of GPS to select the geometric information of a plot, then putting this information into the GIS system for next transaction to produce the new map about the land using.Because the ROM of PDA is very small, it must transact the map of GIS/RS before put into PDA. This will show the map quickly and do not effect the other working of PDA. For the vector map from GIS, here builds a index based on grid, so PDA only needs read a part but not all the data of the map. On the base of the traditional grid, here adds the idea of lay. This method will fix in with the habit to see about map. If a diagram has too many spots, it will be encapsulated by using Douglas-Peucker. For a map of RS, it has too much data for PDA, so integer wavelet is to be used to encapsulate the map.Because the offset , GPS cannot fulfill the demand of the land survey. To deal this problem, DGPS technology is used. So here need a program to receive the data from a GPS receiver which is used as a station. This program needs to save the data as a file for a span to fulfill the different requirement of DGPS.