Research On Selection Model Of Map Loading Adjustment In Quick Mapping

How to generate the variety of multiple small-scale maps from the large scale maps quickly and automatically to satisfy different needs has been a hot research point in nowadays mapping theories and applications. The mathematical research about the translation from large scale maps to small-scale maps has improved a lot. Human-computer interactive operation is one of these achievements. However, the complete automation program for rapid mapping of small-scale is still not accessible. The rapid mapping technology currently distributes more considerations on particular geographical factors rather than the relationship among the elements. Based on this consideration, it leads this paper to the method of map loading adjustment from small-scale maps to smaller-scale maps. As part of the national 863 project, the mathematical research is launched by using residential points, roads and water systems as examples.The main contents of research:(1) The establishment of residential point group selection model considering roads as the affect factThe paper introduced a residential point group selection model and made road as the consideration. The built of the model was based on the basic theories and principles of features selection. Also, it was enlightened by the analysis of the advantages and disadvantages of the previous point selecting models. Residential groups'distribute pattern, distribute density and the relationship between road and the points were considered during the built of the model. Distance transform algorithm was used to generate obstacle Voronoi diagram, by which the important points on the convex hull of point group could be accessible. As a matter of that, the features of the shape and structure of residential group will be maintained. The automatic clustering of point-like entities is implemented. The selection of the density of local point group is achieved though zoning by density of point group.(2) The establishment of road network selection model based on meshAs doing the road network selecting research, the existing methodology of road network selection should be concerned. Other factors such as the original geographical characteristic of the mapping area should also be mentioned. As a result, the paper chooses to select the important roads first and reserve the roads which have the priority in terms of rank or length. The features of geometry and density distribution of the road network can be maintained based on the mesh.(3) Research on algorithm of polygon skeleton line extractingThe planar geometric entities need to be singled when there have greatly changes of scale. The singling of planar geometric entities is actually the problem of polygon skeleton line extracting. It has been a hot research point in this area. The paper provided some ideas of the new version of the algorithm in terms overcoming some shortcomings of the existing methods and considered maintaining the original skeleton line as the bottom line. This improvement would make the skeleton more responsive to the specific applications.The paper provided the ideas of establishing and achieving the residential point group selection model considering roads as the affect fact create the road network selection model based on mesh and the generating of the algorithm of polygon skeleton line extracting. The final practical application shows the selected models affected the results effectively.