Collection Method Of Change-only Geomorphological Information Based On Pda

Change-only information Collection is the first step of updating topographic database. The more current the geomorphological data is, the more valuable the data is. A growing number of organizations and individuals increasingly focus on the current of the topographic data. Nowadays,the main task of surveying and mapping departments in many countries is to constantly update the established topographic databases and provide users with the current data.Therefore,these departments should constantly determine the changes of features in the real world, update the topographic database by collecting change-only information.Geomorphy is one of the most fundamental factor in geomorphological features.Geomorphological data also plays a very important role in updating topographic database.In the recent years, the fast developing technologies in PDA and spatial information collection ,give people the opportunity to improve the technology of surveying and mapping. A change-only geomorphological information's collection approach based on PDA is proposed in this paper. The main works finished are listed as follows:1. At first, the change type and event type of geomorphy are analyzed thoroughly,and an identification method of discriminating geomorphological element is presented.2. During the information collecting process, there should have a set of algorithms.So many algorithms are presented, which are divided into two kind of situations. Aiming at the situation with contour lines without TIN data,an efficient fusion algorithm between the regional changed contour lines and neighboring contour lines based on the line / line topological relationship is introduced in this paper. Aiming at the situation with both contour lines and TIN data, an efficient algorithm based on the points and constrained segments which are inserted or deleted to resolve the fusion matter between the regional changed geomorphological data and neighboring geomorphological data is particularly presented.3. Finally, a prototype system is developed using Visual Studio 2005 and embedded technology on the platform of MapX Mobile, to examine the methods and models presented in this dissertation. Experimental results with the practical and simulated spatial data show the reasonability and practicability of the change-only geomorphological information's collection approach presented in this paper.The proposed approach is operational. The results of this study provide a new way for the design and implementation of such system.