An automated Approach for Labeling Raster Digitized Contour Maps

Con autorización de la revista para este artículo.The substantive pre-processing invariably required by current methods to convert scan-digitized contour maps into a digital elevation database severely limits the use of raster scanning for many practical applications. This paper presents an efficient "raster based approach to label contour lines digitized from topographic maps. In contrast to the predominantly "vector based" techniques currently in use to scan and capture topographic data from hard-copy contour maps, the proposed method uses a semi-automatic "batch-oriented" strategy. The key to the method is the use of graph theory to reconstruct the topological adjacencies of elevation regions in rasterized contour maps. The approach was successfully tested on a prototype scale in digitizing several map segments with terrain slopes ranging from flat to highly mountainous areas. In addition to a significant reduction in the time required to digitize and label scanned maps, from the order of weeks to a few hours, a major strength of the designed approach is the potential of using the many inexpensive raster scanners that are now easily coupled to desktop microcomputers. The proposed method is therefore not only well suited to reduce the associated costs of digitizing maps on a large scale within large organizations, but is also attractive to the many small and medium sized organizations that have so far not been able to take advantage of available digitizing technology.Funding for this research, received through NASA grants NAGW-33, SUP No. 4, and NAGW-512, is gratefully acknowledged. We are grateful to Professor Robert M. Ragan for his encouragement and guidance during the research. Our thanks to Professor Richard H. McCuen, University of Maryland, for his helpful suggestions.Peer reviewe