Enhanced Contour Lines

The United States Geodetic Survey (USGS) is responsible for creating the contour lines that are part of every topographic map. The lines are extracted from other elements and digitized to give model makers the elevation and location data needed to create digital elevation models (DEM), hillshades and triangular irregular networks (TIN) which show in different ways what the terrain looks like in three dimensions.

We started with USGS twenty foot (vertical) contours and added "filler" lines to smooth out the river and compensate for "holes" which the surface interpolation software initially produced. The Pittston inset of the overview contour map shows the unenhanced lines.[Back to pictorial guide main page]

Contours

DEM

Hillshade

Shaded DEM

Shaded DRG

TIN