datum plane

noun

1. surveying the horizontal plane from which heights and depths are calculated

Example Sentences

Usually the contour has labeled on it in figures the height above some starting point, called the datum plane—generally sea level.

From Project Gutenberg

The contours on maps are always numbered, the number of each showing its height above some plane called a datum plane.

From Project Gutenberg

In all maps that are to be contoured some plane, called the datum plane, must be used to which all contours are referred.

From Project Gutenberg

A datum plane, or reference surface, from which all elevations are measured up to the ground surface must be assumed.

From Project Gutenberg

C, at 100 ft., or greater if necessary to place the datum plane below the ground level at all points within the area to be mapped.

From Project Gutenberg