Elevation contours extraction from a color-coded relief scanned map (TA-P8)

Author(s) : Carol Rus (Technical University of Cluj-Napoca, Romania) Corneliu Rusu (Technical University of Cluj-Napoca, Romania) Jaakko Astola (Tampere International Center for Signal Processing, Finland)

Abstract : The focus of this paper is in extracting the elevation contours from a color-coded relief map. The map is preprocessed using a WHMM based algorithm for denoising. Then a linework removal algorithm -- that uses a vector angle edge detector with a saturation-based combination of hue and intensity planes -- is applied. Each distinct elevation region must be solid colored using distinct colors. In order to achieve this, for the printed scanned map, we used a median filtering, and a color clustering process -- based on a minimum variance quantization algorithm. The gaps filling problem can be solved with a multi-pass majority filter algorithm. The elevation contours are extracted by detecting the borders between colors.

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