Louisiana Administrative Code
Title 43 - NATURAL RESOURCES
Part XXVII - State Lands
Subpart 1 - Land Information Mapping and Map Records System
Chapter 3 - Mapping Accuracy
Section XXVII-311 - Map Accuracy Test

A. Testing for horizontal accuracy compliance shall be performed 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) 1984 Standards and Specifications for Geodetic Control Networks to achieve standard deviations equal to or less than the one third of the limiting positional error selected for the map. The distance between control points used in the FGCC Standards for the design of the survey shall be the horizontal ground distance across the diagonal dimension of the map sheet.

B. Testing for vertical accuracy compliance shall be performed by comparing the elevations (Z coordinates) 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 horizontal error in position. The vertical check survey shall be designed according to FGCC Standards to achieve errors in elevation differences at check point locations no larger than one tenth of the contour interval. The distance between vertical benchmarks 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.

C. Discrepancies between the X, Y or Z coordinates of ground points as determined from the map and by the check survey that exceed the limiting error shall be considered unacceptable and will be corrected before the map is considered to meet these standards. The same survey datums, both horizontal and vertical, must be used for both the project and the check control surveys.

D. At least three percent of the total area mapped shall be selected at random and tested for compliance with these standards. A minimum of 20 checkpoints shall be established throughout the area covered by each map sheet selected. At least 20 percent of the checkpoints shall be located in each quadrant of the map sheet and these points shall be spaced at intervals equal to at least 10 percent of the map sheet diagonal.

E. All maps produced according to this accuracy standard shall include the following statement in the title block:

"THIS MAP COMPLIES WITH NATIONAL MAP ACCURACY STANDARDS."

F. Individual map sheets checked and found to conform to this accuracy standard shall include the following statement in the title block:

"THIS MAP WAS CHECKED AND FOUND TO CONFORM TO NATIONAL MAP ACCURACY STANDARDS."

G. When a published map is an enlargement of an original map manuscript or associated digital database, that fact shall be stated in the legend. For example:

"THIS MAP IS AN ENLARGEMENT OF A 1:1,200 ORIGINAL MAP MANUSCRIPT."