PRECISE PHOTOGRAMMETRIC DETERMINATION OF SECTION CORNERS

THIS INVESTIGATION CONCERNS THE RELATIVE ACCURACY OF POSITIONS OF CADASTRAL MONUMENTS DETERMINED BY PHOTOGRAMMETRIC METHODS AS COMPARED WITH FIELD METHODS. THIS IS AN APPLICATION OF NUMERICAL PHOTOGRAMMETRY IN CONTRAST TO TRADITIONAL PHOTOGRAMMETRIC MAPPING PROCEDURES. A SECOND- ORDER GROUND CONTROL SURVEY, ESTABLISHED ON THE STATE PLANE COORDINATE SYSTEM, WAS MEASURED THROUGH THE PROJECT AREA. THIS CONTROL WAS SUFFICIENT FOR PHOTOGRAMMETRICALLY POSITIONING 72 SECTION AND QUARTER-SECTION CORNERS. THE 72 CORNERS WERE ALSO TIED TO THE CONTROL BY CONVENTIONAL FIELD SURVEYING METHODS AS A BASIS FOR COMPARISON OF THE PHOTO- GRAMMETRICALLY DETERMINED PLANE COORDINATE POSITIONS. EACH OF THE CORNERS AND THE SELECTED GROUND CONTROL MONUMENTS WERE PREMARKED WITH PHOTOGRAPHIC TARGETS FOR POSITIVE IDENTIFICATION ON THE AERIAL PHOTOGRAPHS. TWO SCALES OF AERIAL PHOTOGRAPHY WERE EMPLOYED. EACH SCALE OF PHOTOGRAPHY WAS USED IN TWO DIFFERENT PHOTOGRAMMETRIC SYSTEMS. THUS, FOUR SETS OF INDEPENDENT POSITION VALUES WERE DEVELOPED. THE SYSTEMS EMPLOYED WERE INSTRUMENTAL PHOTOGRAMMETRY USING A ZEISS STEREOPLANIGRAPH, AND ANALYTICAL PHOTOGRAMMETRY USING A MANN MONOCULAR COMPARATOR. THE RESULTS SHOW THAT ERROR PROPAGATION WAS NOT PROPORTIONAL TO THE SCALE OF THE PHOTO- GRAPHY. HOWEVER, USING THE SCALES AND PROCEDURES DESCRIBED, THE RESULTS IN ALL CASES, ARE CONSIDERED ENTIRELY ADEQUATE FOR THIS TYPE OF CADASTRAL SURVEY. COST RECORDS SHOW THAT THE FIELD METHOD COSTS WERE ABOUT 200 PERCENT GREATER THAN THE PHOTOGRAMMETRIC METHOD COSTS. /AUTHOR/