Fresh island perspective
Although it is hard to dispute the beauty of the Florida Keys’ lush vegetation and vibrant colors, the coastal nature of the region presents challenges when surveyors want to map the area. “The orientation of the islands has made it very difficult [to create] a uniform, detailed base map upon which to build other essential data layers, such as an accurate parcel layer,” says Kim Rohrs, a senior geographic information systems (GIS) planner for Monroe County’s Growth Management Division. “Without a solid anchor point, our data layers were kind of ‘floating’ in the GIS.”
Monroe County incorporates the Florida Keys, a necklace of about 822 islands. Thousands of visitors become full-time residents each year, keeping the Monroe County Property Appraiser and the Growth Management Division busy maintaining property data and planning for growth. Both tasks, however, have been difficult to manage effectively, Rohrs says, because of geospatial data inconsistencies and inaccuracy caused by the islands’ difficult terrain.
In late 2005, the county and the Florida Department of Transportation (FDOT) District VI pooled resources to acquire aerial imagery to build a seamless base map. They commissioned Dayton, Ohio-based Woolpert to produce high-resolution orthophotographs of the 843 square miles of the Florida Keys. Field crews began setting surveying controls on the ground in February 2006, and then a Leica ADS40 sensor collected both true color and false-color infrared imagery aerially. Leica GPro software and a digital terrain model were used to process the digital imagery into a seamless mosaic of half-foot resolution orthophotos. By February 2007, the county and FDOT began integrating the imagery with the county’s ESRI ArcGIS and FDOT’s Microstation and ESRI ArcMap software.
The datasets have been used to help build a common, precise base map of the region. Users have identified scores of inaccuracies in previous data, but now they can rectify them. Most importantly, Rohrs says, they have the core they need to begin managing the area’s growth. “Because we didn’t have a good base map to work from, we were relatively stagnant in our development and planning,” Rohrs says. “We were just maintaining the status quo. The [new] imagery has completely re-energized the department and allowed us to begin a number of new planning initiatives.”
The imagery is being shared with other agencies, and the county aims to develop a central GIS repository, complete with the orthophoto base map, for other agencies’ use.
Monroe County, Fla.
Growth Management Division
Dayton, Ohio-based Woolpert; Atlanta-based Leica Geosystems; Redlands, Calif.-based ESRI; Exton, Pa.-based Bentley Systems