Graphic display techniques

Traditional maps are abstractions of the real world, a sampling of important elements portrayed on a sheet of paper with symbols to represent physical objects. People who use maps must interpret these symbols. Topographic maps show the shape of land surface with contour lines. The actual shape of the land can be seen only in the mind's eye. Graphic display techniques in GIS's make relationships among map elements visible, heightening one's ability to extract and analyze information.

Two types of data were combined in a GIS to produce a perspective view or a portion of San Mateo County, California. The digital elevation model, consisting of surface elevations recorded on a 30-meter horizontal grid, shows high elevations as white and low elevation as black.

The accompanying Landsat Thematic Mapper image shows a false-color infrared image of the same area in 30-meter pixels, or picture elements.

A GIS was used to register and combine the two images to produce the three-dimensional perspective view looking down the San Andreas Fault.

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The content of this page was copied from USGS Website.
For more information please refer to the site: mapping.usgs.gov