Louisiana Administrative Code
Title 43 - NATURAL RESOURCES
Part XXVII - State Lands
Subpart 1 - Land Information Mapping and Map Records System
Chapter 5 - Ground Control
Section XXVII-511 - Horizontal Control

A. All horizontal control surveys shall be established by conventional triangulation, traverse, or Global Positioning System (GPS) techniques, including any combination thereof, as dictated by specific project requirements.

B. Triangulation and traverse surveys shall be performed in accordance with applicable requirements set forth within the Standards and Specifications for Geodetic Control Networks, as prepared by the Federal Geodetic Control Committee (FGCC), dated September, 1984, inclusive of any and all subsequent revisions in effect at the time such surveys are conducted.

C. GPS surveys shall be performed in accordance with applicable requirements set forth within FGCC publication Geometric Geodetic Accuracy Standards and Specifications for Using GPS Relative Positioning Techniques, Version 5.0, revised August 1989, inclusive of any and all subsequent revisions in effect at the time such surveys are conducted.

D. All horizontal control established shall conform to the minimum requirements for Second Order Class II surveys as set forth within the FGCC Standards and Specifications, and shall result in a minimum distance closure accuracy of 1:20,000. Any surveys originated from sparse or distant existing horizontal control monumentation shall be performed to a higher order of accuracy as may be required to ensure compliance with these standards.

E. Horizontal control surveys performed for the purpose of establishing new permanent horizontal control monuments will be submitted to NGS for verification and publication as part of the National Horizontal Reference Network. Strict compliance to FGCC Blue Book Specifications must be adhered to and all data shall be submitted in accordance with NOAA Manual NOS NGS 2, Input Formats and Specifications of the National Geodetic Survey Database; Volume 1- Horizontal Control Data.

F. All additional temporary photo control points required for photogrammetric control and analytic aerial triangulation shall be established and pretargeted prior to photography. All temporary control points established shall be clearly documented by appropriate descriptions referenced to landmarks and identified by field survey ties to three or more discrete photo image points in the immediate vicinity. In the absence of discrete reference points in the immediate vicinity, collateral ties shall be made to recoverable markers or stakes set and established adjacent thereto.

G. Both conventional and GPS surveys shall start and end on existing NGS control. All field traverses will be a closed loop or otherwise shall close on an adjacent existing NGS horizontal control station. If a new station or temporary photo control point is established in the vicinity of an existing horizontal control monument, direct observations between the two positions must be made whenever the distance between them is less than 20 percent of the shortest distance as measured over the proposed and/or established survey lines (20 percent rule).

H. The spatial distribution, quantity and configuration of all pretargeted horizontal ground control positions established shall be sufficient to facilitate analytic aerial triangulation and subsequent digital map compilation in conformance with these standards. Regardless of terrain configuration, the minimum spatial distribution of pretargeted horizontal ground control positions to be established within and adjacent to any project area shall be such that photo-identifiable ground control points will be established along every other flight line at intervals not to exceed five contiguous photogrammetric stereo models regardless of scale.