基于数字高程模型数据绘制立体地貌图方法

地貌晕渲图是一种较常见的数字测绘产品，它通过模拟阳光入射产生的明暗程度反应地貌的分布、起伏和形态特征。近年来随着三维可视化技术的发展，具有更加丰富地形地貌信息的立体地貌图逐渐为人们所关注。本文研究了不同高度比例因子曲线的渲染效果，通过基于B样条函数控制的变比例因子调整地貌晕染，改善了渲染区域中平缓地形及高低起伏地形并存情况下的立体显示效果。通过行列扫描并设定不同阈值进行水域识别，避免了虚警。首次提出通过设定红色阈值抑制偏色，有效地解决了红青分色立体地貌图制作过程中出现的偏色问题。实验结果表明：该方法能够有效的改善地貌图晕染效果；可在保证高色彩还原的前提下提高地貌图立体显示效果。

Drawing 3D Geomorphologic Map Based on Digital Elevation Model Data

Relief shading maps is a common digital mapping product that reflects the distribution, undulation and morphological characteristics of the geomorphic by simulating the brightness produced by light incidence. In recent years, with the development of 3D visualization technology, the three-dimensional relief shading map with more abundant topographical information has been gradually attracting people''s attention. This paper studies the rendering effects of different height scale factor curves. Based on the B-spline function control, the variable scale factor adjusts the relief shading, which improves the display effect of the flat terrain and the undulating terrain in the rendering area. The false alarms can be avoided by scanning the rows and columns and setting different thresholds for water identification. It is proposed for the first time to suppress the color cast by setting the red threshold value, which effectively solves the color cast problem. The results show that this method can effectively improve the smearing effect of the topography. It is concluded that this method can improve the three-dimensional effect of the topography under the premise of ensuring high color reproduction.