The Data Acquisition On Land Resource Investigation Based On GPS-PDA

In recent years, with the rapid development of 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 location. 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. Land resources are essential to human survival. Catching current status of land resources and information of land change is the basis for constituting an overall plan of land use and making decisions on land. In order to enhance the efficiency of land change survey, the paper designs a Land Change Survey System on Palm (LCSSP). Based on PDA, the system integrates GPS and PDA, which adopts real time differential process to improve positioning precision. Under Windows.CE.NET environment, functions of the system, such as land change survey, GPS data process, vector data edit and so on, are developed by using eVC, C#.NET program language. LCSSP fundamentally solves some inherent problems including long cycle, low efficiency, low precision and etc. in land change survey. In this text, LCSSP is an applications based on PDA and specially use in land resource investigate data acquisition, and it 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 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++ 4.0\Windows Mobile 5.0 platform ,and further studying the serial communication and encoding between GPS and PDA and GPS Intermediate Driver. This text also analysis of the four parameters for the project under the conditions of how the coordinate transformation; analysis of the two models of GPS positioning accuracy, and the improved method.