The Research And Implement On Land Resource Investigation System Based On PDA

In recent years, the rapid development to mobile computing, the constant mature and the rapid use in each trade of geographical information system (GIS) , global positioning system (GPS) and remote sensing (RS) have offered powerful technical support for the fact that adopt the embedded technology and develop the geographical information service based on position. The appearance of the palmtop computer (PDA) becomes the remedying and extending in human life of PC and Internet. That can meet people's needs for calculation everywhere. Country's on-going digitized strategy require each trade to realize the informationization and digitization, for instance, the instance digital city , digital traffic and perfect agriculture, etc. These fields are all to adopt RS, GPS to obtain the data, to adopt GIS to store, deal with the data, to draw support from such means as computer network and communication and to offer decision support for finally realizing information processing and analyse. In this text, land resource investigation system is an internet applications based on PDA and specially use in land resource investigate. Integrating RS, GPS and GIS, it can show the remote sensing picture of various kinds of space resolution ratio RS map and scanned topographic map, can carry on the mutual inquiry of the space figure and attribute data, can accept GPS satellite signal, can load the vector thematic picture layer, gather the on-the-spot data and can calculate the distance and area. It has realized the mobile computing technology to apply to traditional space information service, has changed the traditional mechanism of service based on position completely. This system can change the land resource with the current backward investigate mode and promote the development of agriculture informationization. This text mainly research the thinking of embedded software development and the difference between it and desktop software development; has designed every function module of the system in detail; has given the method of developing GIS in eVC++ 3.0 platform, further investigated the arithmetic of the mouse choosing simple polygon and the arithmetic of polygonal algorithm of area by calculating constant points; has compared ODBC, DAO and ADO three data access technology and realized ADO data access; has analysed the precision of GPS and given some methods to improve it.