The Graphic Overlay Method

Elevation Map Examples
Homepage  |  Introduction  |  Map Features  |  Feature Measurements  |  Coding
Value Added Maps  |  Elevation Maps  |  Soil Survey Maps  |  Soil Attributes
Soil Characteristics  |  Combining Strategy  |  Process Map  |  Solution Map

Topographic "elevation" maps describe the relative height of land above mean sea level (msl).  These maps (below) represent an area of approximately 640 acres and are hand coded to emphasize "specific features" (to be used in the coming examples).  
Uncolored topographic elevation.   

These Topographic Map examples are small portions (Section 28) of the USGS Forest Hill, LA (1:24,000).

Topographic elevation colored according to the 10 foot differences in elevation (above mean sea level).  

The coding logic follows the scheme..., lighter colors are the highest elevation and darker colors are the lowest elevation.

A green color is assigned to emphasize elevations above 150 feet msl.  In the coming example, the example criteria requires areas above 150 feet.  

One way of emphasizing the land that is "needed" is to remove (color black) the areas that do not fit the criteria, as in the example below.

The color Black indicates areas that are not needed (desired) for this particular example. Using the reverse logic..., "Black areas, are areas you don't want"  (The color black eliminates elevations below 150 feet msl).  

This map is used in the (coming) map combining example.

The Soil Map is the second Value Added example.  

Return to the Graphic Overlay Homepage 

All contents copyright (C) 1993-1999,  D. Fehler  All rights reserved.