Development of Automatic System for Producing High-resolution DEM from Topographic Map and its Application

我们推动了本项目的工作，开发了一个从市面上出售的地形图自动生成高分辨率数字高程模型(DEM)的系统，具体如下：(1)对许多真实地形图进行了测试，提高了所采用的算法的性能；(2)我们将系统集成成一个完整的、用户友好的系统；(3)我们提供了高分辨率的DEM，并开发了有效提取地物的工具。首先，我们提出了两种数字高程模型的后处理方法，扩展的Grimson正则化方法和限制光滑化方法，可以去除数字高程模型上的非自然形状，如水平急剧下降、凹凸不平和凹陷。从评价实验中，我们发现它们是有效的。文中还讨论了地形图的平差问题，即地形图的边界可能会稍有不同，需要对其等高线进行调整才能形成统一的DEM。第二，我们继续使用图形用户界面(GUI)技术实现系统，以实现用户友好的系统。此外，我们正在努力将我们的系统整合为一个完整的、用户友好的系统。第三，我们提供了高分辨率的DEM，并开发了有效提取地形特征的方法。现在，我们可以说，我们的系统的核心是从地形图等值线地图生成高分辨率DEM。我们将继续丰富该系统，并将其应用于地理信息系统中地形信息处理的实际问题。

We have pushed our work in this project to develop an automatic system producing high-resolutional digital elevation models (DEM) from topographic contour maps on sale, as follows: (1) testing the system to many real topographic maps, we improve performance of the adopted algorithms; (2) we integrate the system to be a total and user-friendly one; (3) we provide high-resolutional DEMs and develop tools to extract effectively the topographic features. For the first, we developed the two post-processing methods on DEMs, the extended Grimson's regularization method and the restricted-smoothing method, that can remove unnatural configurations on DEMs such as sharp drops in level, bumps and hollows. From the evaluation experiments, we found that they are effective. Also, we discussed the adjustment problem of topographic maps that there may be a little different in their borders and it is necessary to adjust their contours to make a unified DEM. For the second, we have continued implementation of the system using graphic-user-interface (GUI) techniques to realize a user-friendly one. Also, we are making an effort that our system may be integrated to be a total and user-friendly one. For the third, we provided high-resolution DEMs and develop the methods to extract effectively the topographic features. Now we can say that the core of our system producing high-resolution DEMs from topographic contour maps is accomplished. We will continue our works to enrich the system and apply it to practical problems of topographic information processing in GIS.