Tests for compliance of a map sheet are optional. Testing for
horizontal accuracy compliance is done by comparing the
planimetric (X and Y) coordinates of well-defined ground points
to the coordinates of the same points as determined by a horizontal
check survey of higher accuracy. The check survey shall be
designed according to the Federal Geodetic Control Committee
(FGCC) [FGCC, 1984] standards and specifications to achieve
standard deviations equal to or less than olle-third of the "limiting
rms error" selected for the map.The distance between control
points (d) used in the FGCC standard for the design of the survey
shall be the horizontal ground distance across the diagonal
dimension of the map sheet.
Testing for vertical accuracy compliance shall be accomplished
by comparing the elevations of well-defined points as determined
from the map to corresponding elevations determined by a survey
of higher accuracy. For purposes of checking elevations, the
map position of the ground point may be shifted in any direction
by an amount equal to twice the limiting rms error in position.
The vertical check survey should be designed to produce rms errors
in elevation differences at check point locations no larger
than 1/20th of the contour interval. The distance (d) between bench
marks used in the FGCC standard for the design of the vertical
check survey shall be the horizontal ground distance across the
diagonal of the map sheet. Generally, vertical control networks
based on surveys conducted according to the FGCC standards for
Third Order provide adequate accuracy for conducting the vertical
check survey.