Using "Bump Mapping" Techniques in Cartographic Backdrops
Bureau of Land Management
Shaded or painted relief backdrops can add tremendous visual interest and value to cartographic products. Relief backdrops have proven to be an effective method for portraying realistic landscapes and geographical situations. This technique is widely practiced in cartography today. However, the beautifully smoothed and colored shaded relief surfaces commonly portrayed as backdrops on many maps often do not reveal additional information widely available through interpreted satellite imagery or other geographical sources. This subtle, yet important information can be brought to life through bump mapping. In traditional 3d graphics applications, bump mapping is defined as a process that interprets changes in an object's surface luminance or color values and modifies elevations on the objects surface accordingly. Bump mapping for cartographic purposes is the process of combining surface materials and landscape textures with tinted thematic information to create an illusion of texture on surface relief. Satellite imagery, such as Landsat Panchromatic 15 meter data, is a good source for "bump mapping" vegetation and land cover themes, since the satellite measures the surface reflectance and texture of the Earth's surface materials. This presentation will demonstrate the application of bump mapping for mountain cartography and present several hard copy posters for viewing.