Research On Large-scale Map Generalization For Settlements Based On NewMap

With the rapid development of computer graphics technology, the establishment of map database and Geographic Information System, cartographic generalization from the traditional artificial era into the digital era. In the digital environment, due to the different importance of application goals and objectives, and then affecting the expression form of the target on the map. This creates a multiple-scale representation of the target problem. In order to meet the national economy and social development demand for geographic data updating.Many country set a short update cycle of large scale map data. Therefore, construction of multiple-scale geographical spatial database and real-time updates become a increasing onerous heavy task. As the core part of cartographic generalization and an important means of map data production and updates, extraction of feature information, visualization and Geo-scale analysis. Automatic map generalization has become a key issue to be solved.This paper focuses on the research of the building polygon merging in the large scale of residential, simplification algorithm. And they are designed and implemented based on the basic algorithm in WJ-III Map workstation of NewMap. The main contents and features of the paper are as follow:(1) Paper presents and established an improved method of the detection of proximity relationship between Residents. Build block surface according to the auxiliary data of road data, and it extract residential buildings by using the built block surface. With block surface as a unit, threshold of merger as judgment indicator, based on the innovative method of the paper, merging each unit of the building in residents separately to improve the universality of algorithm.(2) Paper presents and established an improved method of the four-near-point method and the skeleton extraction algorithm. According to threshold of the least visible length and polygon area, length, discussing on the classification of polygon, and judging types have been merged of the building in residents. Based on the results of the type of judgment, simplify the merged of the building in residents by using the innovative method of the paper, realized simplifying the merged of the building in residents by considering the global and local at the same time.(3) Based on Microsoft Visual Studio 2010, realized the API of residential generalization by using the C++ programming language, and integrated into the WJ-III Map workstation, it has been used for the large-scale production of Chengdu in Sichuan more than 10,000 square kilometers from 1:500 to 1:2000, 1:5000, 1:10000 map.