基于等高线的黄土高原小流域地形虚拟

Terrain visualization of small watershed in Loess Plateau based on contour lines

黄土高原地形三维虚拟是"数字黄土高原"的基础,可为区域水土保持生态建设提供科技支撑。针对直接在地理信息系统软件中观察三维场景存在的控制交互能力不足问题,提出综合利用地理信息系统软件的地形插值算法,基于MFC框架下的OpenGL程序设计的思路,实现地形的真实感三维虚拟。以黄土丘陵沟壑区康家沟小流域为例,等高线数据在AutoCAD和ArcView软件中处理,生成ASCII格式的规则网格DEM数据,依据它们绘制三角形带,采用加权平均法求得各点的法向量,设置光照与材质模式,添加动态天空背景,实现了该流域地形的真实感三维虚拟,并增加交互能力,完成自由漫游与多角度观察。

The terrain three-dimensional visualization of Loess Plateau is a basal research for ＂Digital Loess Plateau＂, which can provide scientific information for research of soil and water conservation. From viewing three-dimensional scene directly in GIS （Geographic Information System） software, it cannot give enough information of interactive communication. To solve that problem, a new means to visualize real sense terrain was supposed in this paper. It combined terrain interpolation algorithm in GIS software with OpenGL programming based on MFC. With the example of Kangjiagou watershed, the contour line data were preceded in AutoCAD and ArcView software to create regular grid DEM （Digital Elevation Model） data of ASCII form. Drawing triangle strip according to those data, calculating the normal value of each point with weighted average model, setting lighting and material model, adding dynamic sky background, making wander scene and view in different directions successfully combined with interactive function, all these ways to make sure the real sense three-dimension visualization of the small watershed had implemented well.