2001 Digital Elevation Contours
In 2001, the North Central Texas Council of Governments facilitated the purchase of digital elevation contours for the following five counties in North Central Texas: Collin, Dallas, Denton, Rockwall and Tarrant. The contours were captured coincident with the 2001 digital aerial photography using light detection and ranging (LIDAR) and are available at two-foot intervals. The contractor for this project was Vargis, LLC.
Digital elevation contour products can be purchased through the DFWMaps Marketplace.
2-Foot Digital Elevation Contour Sample [Shapefile]
2-Foot Digital Elevation Contour Sample [ArcInfo export format]
2-Foot Digital Elevation Contour Sample [AutoCAD dxf format]
LIDAR grid - Shapefile, DXF file, Tile Naming Convention
Specifications
NCTCOG's contour products include digital elevation models (DEMs) and 2-foot contours. The terrain information used to generate the DEMs and contours was captured using an airborne Light Detection and Ranging (LIDAR) system. The collection and production conforms to the following specifications:
| Sensor Type | Airborne LIDAR |
| Altitude of Capture | 8,000' above mean terrain |
| Capture Period | November 2000-January 2001 |
| Control Sources | Ground survey, airborne GPS and inertial measurement |
| DEM Point Spacing | 3-5 meters (9.8-16.4 feet) |
| DEM Point Accuracy | 15-20 cm (5.9-7.8") vertical on clearly defined ground features |
| Contour Interval | 2 feet |
| Coordinate System | Texas State Plane, North Central Zone |
| Horizontal Datum | NAD 83 |
| Vertical Datum | NAVD 88 |
| Units | US Survey Feet |
| DEM Format | ASCII |
| Contour Format | ArcInfo |
The LIDAR data were collected and processed under the supervision of Certified Photogrammetrists and Licensed Surveyors. The raw data were edited to remove above-ground features. The DEM and contours were interpolated from the LIDAR data and interactively edited to create a seamless and consistent coverage. Every fifth contour line is designated as an index and annotated. The contours are guaranteed to meet National Map Accuracy Standards at 2-foot intervals.