国家西部测图工程1:50000晕渲地形图研究

为向用户提供内容更加丰富的新型GIS产品,国家西部测图工程提出在生产1:50000线划地形图产品的同时,生产1:50000晕渲地形图产品。本文首先提出了1:50000晕渲地形图的内容及表达规则,在此基础上根据西部区域特点,分析了晕渲生成相关参数,提出西部测图工程1:50000晕渲采用斜照光源、光源方位角315°、光源高度角55°、垂直比例因子为1。其次提出了晕渲生成后的图像分辨率调整、色调调整,基本地理要素与晕渲图像叠加处理。最后提出1:50000晕渲地形图图外整饰原则。该试验的研究结果已形成生产技术文件,并应用到国家西部测图工程中。

Hill-shading topographic maps production in the western mapping project

In order to provide users with more diverse varieties of new GIS products that contain richer content,it is proposed that hill-shading topographic maps should be produced as producing the DLG topographic maps offered in the 1:50 000 topographic mapping of blank areas in the western region,China.The paper first introduced the contents contained in the hill-shading topographic mapping and principles about how to represent these contents.Then,the main points of designing Hill-shading topographic maps were given,including how to select related parameters used for Hill-shade production,how to adjust the resolution and tone of hill-shade image produced,how to deal with overlay relations between features,and how to decorate hill-shading topographic map.Now,the technical specification document has been put forward based on some experiments,and the study result has been applied to the 1:50 000 topographic mapping of blank areas in the western region project.