Regular Grid DEM Data Compression by Using Zero-Crossings: The Automatic Breakline Detection Method
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Date
1991-11
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Ohio State University. Division of Geodetic Science
Abstract
This report presents an automatic method of extracting Breaklines and Breakpoints from a set of regular grid DEM data. The regular DEM data are considered as an array of signal which can be convolved by the Laplacian of Gaussian (LoG) filter. It is found that points having positive maximum or negative minimum convoluted values(extremas) between zero-crossings of LoG are located at places critical for terrain description. The extremas obtained by the proposed method correspond to breaklines and breakpoints of the terrain. These breakpoints and breaklines contain explicit information and have more meaning than regular grid points. Based on the concept of using breaklines and breakpoints as the terrain relief representation, the proposed technique can be considered as a DEM data compression process. This work shows that contour maps constructed from the extracted breaklines and breakpoints exhibit similar terrain roughness as the ones constructed from the full DEM data. The results justify the possibility of implementing this concept. Furthermore, breaklines and breakpoints obtained by this technique are almost identical to the ones manually collected by human operators.