Study On The Method Of Automatic Thematic Map Layout

With the rapid development of computer technology,earth observation technology and geographic information system technology,geographic information service has been rapidly integrated into people's lives.Map,as one of the main forms of geographic information service products,people's demand for its kind and quantity is higher and higher.Therefore,map design is a very important task,especially the design of thematic map.The automatic layout design is a key to improve the efficiency of thematic map design.The layout design is the design for the location,size and form of the map name,map margin,legend,chart,scale and various instructions,which needs to make full use of the map surface.For the map with the main area,it also includes the location of the main area on the map,which is an important part of mapping and is also the key link in the process of map output.Therefore,the automation of map layout can be used to promote the automation of cartography.On the basis of analyzing the research results at home and abroad,this paper attempts to use the map layout configuration and visual balance theory to propose a method that relies on the layout template to automatically search the appropriate location of map elements and evaluate them quantitatively.From the actual needs of the production of thematic maps,this method takes into account the factors such as the size of the paper and the scale of the map,and the size and position of the map elements are expressed by a rectangular in order to simplify the design process.According to the knowledge of map layout configuration,a variety of layout template library is constructed and is classified by the rectangle features of the main map,Finally,a most suitable layout template is found for the current main map in the template library.Finally,in the CorelDRAW environment,VBA technology is applied to implement the proposed method.The main contents and innovation points of this paper are as follows:(1)The influence of paper size,map scale and visual center on the layout are comprehensively considered.Computing the visual center of the main map and move it to the center of the layout center.In addition,the function of automatically calculating the maximum scale for users is designed.the maximum scale function is designed for the user to realize the automatic displacement and scaling of the main map.(2)Varied layout template libraries are created for different main maps and map elements.The graphic configuration rules and the rich practical experience of the cartographic experts are formalized and visualized,so that the knowledge and experience of the map design can be shared and the efficiency of map mapping is improved.(3)According to the different main map,the rectangle of each element in each layout template is detected,and the appropriate location is searched automatically.Finally,the visual balance evaluation model is used to evaluate the suitable layout,and the qualitative evaluation of the visual balance is transformed to the quantitative evaluation.