1.1 Location Errors Using Secondary
Data Sources
How well should the digitized map match the
source map? There are no federal standards on
the threshold value. A geospatial data producer
can decide on the tolerance of location error.
The Natural Resources Conservation Service
(NRCS), for example, stipulates that each
digitized soil line in the Soil Survey Geographic
(SSURGO) database shall be within 0.01-inch
(0.254-millimeter) line width of the source map.
At the scale of 1:24,000, this tolerance
represents 20 feet (6 to 7 meters) on the
ground.