Topographic Contours 2018 - Download

This downloadable zip file contains an ESRI File Geodatabase (FGDB) that is compatible with most versions of ArcGIS Pro, ArcMap, and AutoCAD Map 3D or Civil 3D. To view the geodatabase’s contents, please download the zip file to a local directory and extract its contents. This zipped geodatabase will require approximately 2.85 GB of disc space (3.09 GB extracted). Due to its size, the zip file may take some time to download. This topographic contour layer was derived from LiDAR collected in spring of 2018 by Dewberry Engineers in coordination with Tallahassee - Leon County GIS. The contours were extracted at a 2 foot interval with index contours every 10 feet. Lidar Acquisition Executive Summary The primary purpose of this project was to develop a consistent and accurate surface elevation dataset derived from high-accuracy Light Detection and Ranging (lidar) technology for the Tallahassee Leon County Project Area. The lidar data were processed and classified according to project specifications. Detailed breaklines and bare-earth Digital Elevation Models (DEMs) were produced for the project area. Data was formatted according to tiles with each tile covering an area of 5000 ft by 5000 ft. A total of 876 tiles were produced for the project encompassing an area of approximately 785.55 sq. miles. THE PROJECT TEAM Dewberry served as the prime contractor for the project. In addition to project management, Dewberry was responsible for LAS classification, all lidar products, breakline production, Digital Elevation Model (DEM) production, and quality assurance. Dewberry’s Frederick C. Rankin completed ground surveying for the project and delivered surveyed checkpoints. His task was to acquire surveyed checkpoints for the project to use in independent testing of the vertical accuracy of the lidar-derived surface model. He also verified the GPS base station coordinates used during lidar data acquisition to ensure that the base station coordinates were accurate. Please see Appendix A to view the separate Survey Report that was created for this portion of the project. Digital Aerial Solutions, LLC completed lidar data acquisition and data calibration for the project area. SURVEY AREA The project area addressed by this report falls within the Florida county of Leon. DATE OF SURVEY The lidar aerial acquisition was conducted from February 05, 2018 thru April 25, 2018. ORIGINAL COORDINATE REFERENCE SYSTEM Data produced for the project were delivered in the following reference system. Horizontal Datum: The horizontal datum for the project is North American Datum of 1983 with the 2011 Adjustment (NAD 83 (2011)) Vertical Datum: The Vertical datum for the project is North American Vertical Datum of 1988 (NAVD88) Coordinate System: NAD83 (2011) State Plane Florida North (US survey feet) Units: Horizontal units are in U.S. Survey Feet, Vertical units are in U.S. Survey Feet. Geiod Model: Geoid12B (Geoid 12B) was used to convert ellipsoid heights to orthometric heights).