Visualizing topography by openness: A new application of image processing to digital elevation models
2002; American Society for Photogrammetry and Remote Sensing; Volume: 68; Issue: 3 Linguagem: Inglês
ISSN
2374-8079
AutoresR. Yokoyama, Michio Shirasawa, Richard J. Pike,
Tópico(s)Planetary Science and Exploration
ResumoA new parameter, here termed openness, expressing the degree of dominance or enclosure of a location on an irregular surface, is developed to visualize topographic character. Openness is an angular measure of the relation between surface relief and horizontal distance. For angles less than 90, it is equivalent to the internal angle of a cone, its apex at a DEM location, constrained by neighboring elevations within a specified radial distance. Openness incorporates the terrain line-of-sight, or viewshed, concept and is calculated from multiple zenith and nadir angles-here along eight azimuths. Openness has two viewer perspectives. Positive values, expressing openness above the surface, are high for convex forms, whereas negative values describe this attribute below the surface and are high for concave forms. Openness values are mapped by gray-scale tones. The emphasis of terrain convexity and concavity in openness maps facilitates the interpretation of landforms on the Earth's surface and its seafloor, and on the planets, as well as features on any irregular surface-such as those generated by industrial
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