Department of Finance & Administration
Mark Emkes, Commissioner
Elevation Mapping Program
This area contains detailed information about the Tennessee Base Map Elevation Project. You will be able to access supporting documents, status updates, and find the latest information about the Project.
As part of the development of digital ortho imagery associated with the Tennessee Base Mapping Program, a digital terrain model (DTM) was created during initial production. The standard DTM is primarily used for orthorectification, but in selected areas a high accuracy DTM was developed to facilitate development of 2’ contours in selected urban areas at 1:1200 (100’) scale and 10’ contours in rural areas at 1:4800 (400’) scale. These high accuracy DTM’s and contours meet ASPRS class 1 accuracy standards. However, these data products only exist in selected portions of the State. The goal now is to develop standardized digital elevation data products for the entire State that can be used by State agencies and other consumers of GIS data through the TNMap, which will serve as the data access mechanism to the general public and State agencies.
A process using a combination of ArcMap with 3D Analyst extension, Workstation ArcInfo and custom scripting is applied to convert the original .DGN format, first into ESRI Shapefiles, and then into a countywide mosaic of mass points and break lines housed in an ESRI geodatabase. OIR GIS Services is able to generate a countywide triangulated irregular network (TIN) which is then used to create a seamless countywide contour layer using out-of-the-box tools found in 3D Analyst. The resulting contours are clipped at the county boundary and QC’ed in post processing to ensure edge-matching with surrounding counties.
