STEREO MATCHING USING LINE SEGMENTS OF ZERO CROSSINGS 
Anton Schenk: 
Department of Geodetic Science and Surveying 
Ohio State University 
Columbus, OH 43210-1247, USA 
Otto Hofmann 
Messerschmitt-Boelkow-Blohm GmbH 
Postfach 801149 
8000 Munchen, FRG 
Abstract 
For more than twenty years, area correlation has been the preferred 
method in photogrammetry to find conjugent points on digital images. 
While in certain cases this method produces good results, in others, it 
fails. The human visual System is remarkably adept at stereo matching and 
is superior to area correlation. The theory of human vision is understood 
as an information process, and computer models clearly indicate that the 
method of stereo matching is not that of area Correlation. The paper 
Summarizes the most important results, and a new method of matching 
line segments of zero crossings is suggested to precisely determine a 
sufficient number of points for the orientation of images, without the 
need for approximate locations of those points. 
Introduction 
There is an increasing trend in photogrammetry to work with digital 
imagery rather than with analog photographs, be it because some 
applications may quickly require results (real-time photogrammetry), or 
be it simply because of reasons for automating certain photogrammetric 
procedures. Generating a digital elevation model is a typical example of 
attempting to automate a task normally left to an operator. Of the many 
processes involved in dealing with digital imagery, stereo matching or 
the formation of the three-dimensional object space is the most challen- 
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