Screening of Building Edges in Stereo Aerial Images Using Surface Normals as Constraints

• Main Authors: Shin-Chung Chen, 陳世崇
• Other Authors: Shue-Chia Wang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/98911654853159253820

碩士 === 國立成功大學 === 測量工程學系 === 87 === With the progress of the informatic technology, traditional methods of displaying the spatial information on 2D analogue maps have also evolved to 3D display in digital form. Virtual Reality, 3D City Models, etc. are, among others, the examples of this evolution. As a result, how to automatically extract the man-made buildings from aerial images becomes a very important research topic in the field of the Digital Photogrammetry. The automatic building extraction always begins with the extraction of gray level edges. But the gray level edges detected by most edge detecting algorithms are often broken or irrelevant to building edges. In order to cope with these problems, other knowledge should be included to assist the search of the building edges. Digital Surface Model (DSM) is one of them. Digital Surface Model is the representation of the surface height information of the terrain, including the height information of buildings, trees and other fixed objects standing on the ground. Through proper analysis, approximate roof outlines can be detected from the DSM. These outlines can then be used to assist the search of the building edges. In this research we assume that roofs are consisted of simple planar surfaces. Based on this assumption, surface normals which belong to the same planar surface should have same orientations in the space. Therefore we can use the region growing technique to detect the approximate borders of that plane. The results of this research show that under proper conditions, the approximate locations of building edges can be detected. These locations can then be used to screen out gray level edges which do not belong to any buildings.