Multi-scale Expression Of Settlements

Scale is one of the important characteristics of map data.With the development of digital maps and network technology,new requirements have been put forward for the way of browsing map data and the data quality of map data.People are no longer satisfied with the static map reading of single sheets at different scales,but seek a way of map browsing supported by multi-scale expression technology based on automatic cartography synthesis,and the data quality should also take into ac count the needs of visual cognition to realize electronic Stepless zooming of the map,adaptive browsing of the network map,etc.This paper takes residential area elements as an example to study the multi-scale expression method of residential area elemen ts.Based on the Gestalt principle and the basic method of automatic mapping and synthesis,a multi-scale expression model of residential area elements is constructed.The specific research content includes:1)Construct a multi-scale expression model of residential area elements.Through the construction of the model,the user can select the target scale to obtain a comprehensively processed residential map in accordance with the visual cognition at that scale.The multi-scale expression model for resident ial areas is constructed through the process of residential area selection,structural analysis to construct a minimum spanning tree,pruning to obtain clustering results,and comprehensive operations of clustering results.2)Structural control in multi-scale representation.In this paper,the visual distance between neighboring residential areas is obtained through structural control,and based on this,the residential area group MST and pruning threshold are generated to obtain reasonable clustering resu lts.Therefore,structural control occupies an important position in the construction of multi-scale expression models.The structural control of the residential area group in this paper includes the construction of a constrained Delaunay triangle network,the neighborhood map and skeleton line of the residential area are obtained according to the Delaunay triangle network,and the calculation of the Delaunay triangle network and the skeleton line takes into account the neighboring distance of the extension direction of the residential area and the neighboring residential area The similarity between the size,direction,shape,density,etc.,is loaded into the adjacent distance with a certain ratio to obtain the final proximity matrix.3)Research on the comprehensive algorithm of polygon mapping in residential areas.Based on the rectangular characteristics of residential areas,this paper designs and improves the algorithm of residential area merger and simplification respectively.In the study of polygon m erging,the merging process of polygons is regarded as the process of repeated disintegration and reorganization of the polygon coordinate set.First,the convex hull of the two polygon coordinate sets is constructed,and the vertices in the original polyg on are added to the convex hull in batches according to the characteristics of the polygon.And take into account the rectangular characteristics of residential areas to complete the merger process.The simplification of the polygon is based on the "rectangular difference" algorithm,which simplifies the algorithm and makes it more applicable.At the same time,it realizes the hierarchical simplification of residential areas.