地图要素图形冲突处理方法——以线状要素(道路、水系和境界)为例

Handling Graphic Conflicts between Cartographic Features:Exemplifying Geolinear Features(Road,River and Boundary)

按照目前的专业制图规范对地图表达的质量要求,计算机制图原理和技术无法避免制图过程中需要大量人工处理地图要素图形冲突的工作。这种由于数据模型间(数字地理景观模型与数字制图模型间)的差别而产生的技术难题一直是实现快速制图的瓶颈。本文基于"先处理、后符号化"的策略,通过分析引起图形冲突的形式以及地图制图规范对冲突处理的要求,提出了针对图形重叠和图形衔接两类图形冲突处理的基本操作,即将对地图要素(地理要素符号化)的图形处理转变为对地理要素本身的处理,从而减少了后期图形冲突处理的工作量;基于这些基本操作,以地形图制图中产生大量冲突处理的道路、水系和境界要素类型为例,说明如何综合利用这些基本操作,实现对图面冲突自动处理的方法;最后,两幅实际地形图数据试验表明本操作可以提高制图效率。

According to the requi rements of map qual ity by cartographic specifications,the current computer cartographic methodology and technology could not inevitably avoid manual ly intervening in resolving a large amount of graphic confl icts after symbol ization.It results from the differences between Digital Landscape Models and Digital Cartographic Models and has been a bottleneck for fast map-making. Through an investigation into the appearance of cartographic confl icts and cartographic specifications,this article presents a set of basic operations to implement the cartographic strategy “processing before symbol izing”for handl ing graphic confl icts specifical ly on two forms of confl icts:graphic overlap and graphic connection.That strategy translates handl ing graphic confl icts caused by symbol ization of geographic features into processing the features-selves so that a lot of thereby confl icts are removed. Appl ications of those basic operations in resolving cartographic confl icts are outl ined by exempl ifying some typical confl icts caused by the main topographic features:Road,River system and Boundary.Two experiments on producing topographic maps verify the appl icabi l ity of the presented operations as wel l as the paradigm in this study in improving efficiency of map-making.