Louisiana Administrative Code
Title 43 - NATURAL RESOURCES
Part XXVII - State Lands
Subpart 1 - Land Information Mapping and Map Records System
Chapter 11 - Aerial Triangulation
Section XXVII-1109 - Passpoints

A. Passpoint locations will be manually selected by reviewing the control photographs in stereo. Selected passpoints shall be located, symbolized and labeled on the image side of the control photographs. All selected locations will lie on unobscured level ground whenever topographic conditions permit. Particular care shall be taken in selection of passpoints so that in built-up urban areas (and rural when possible), points shall be selected that are field recoverable. Field recoverable points are defined as discrete intersections of linear features such as two sidewalks, sidewalks and curbs, slab corners (parking lots, driveways, etc.), and discrete point features such as manholes, storm drain gratings and other small manmade features.

B. For analytical aerial triangulation, individual frames will carry a minimum of nine passpoints, with the exception of end frames of flight lines which will carry a minimum of six passpoints. One point will lie in the corner of each neat model, and one point will lie near each nadir position of each neat model. It is recognized that deviation from the ideal distribution may be necessary for those photographs covering bodies of water and/or areas of heavy ground cover. Tie points between strips will occur with a frequency of at least one per frame. As a general rule, wing passpoints within lines of flight will also serve as tie points between strips.