Combined Photogeodesy and GPS Network

Manatee County, Florida is building a multipurpose LIS (land information system). To meet the mapping requirements an accurate coordinate base was required. Primary control was established and monumented at or near all township comers, 3‐mi (4.8 km) comers, and center‐of‐township comers. Global positioning techniques were used to establish this network meeting second‐order, class I requirements. Four Trimble Navigation single frequency receivers were used to perform field measurements. Secondary control was to control an aerial photography coverage and provide coordinate estimates on existing comer evidence. The intent of the secondary control network was not retracement, and no comers were proven. Photogeodesy was used to measure the secondary stations. The stations were spaced at approximately 1‐mi (1.6 km) intervals and in the vicinity of section comers. Results indicate global positioning and photogeodesy may provide costeffective methods for providing control for GIS (geographic information system) programs. Future programs should target additional points such as quarter‐ and center‐section comers. Additional points could be targeted and measured for little cost.