DFW Marketplace Product Descriptions Old

Aerial Images – Years 2001 to 2022
NCTCOG's high-accuracy, 4-band orthophotography is captured at either 3" or 6" resolution.   The final aerial photography meets The American Society of Photogrammetry and Remote Sensing (ASPRS) Class I standards and is suitable for engineering grade analysis.  NCTCOG flies orthophotography during the leaf-off season (Dec-March).  The imagery undergoes extensive processing and QC by the chosen vendor before delivering 4-6 months after acquisition. 

Contours Multi-year NCTCOG (LiDAR)
NCTCOG’s multi-year 2’ digital elevation contour layer was developed by bringing together 0.5 Meter LiDAR flown by NCTCOG (shown in shades of blue), 0.5 Meter TNRIS LiDAR and 0.7 Meter FEMA & USGS LiDAR (shown in shades of yellow). The data was flown from 2009 to 2019 and represent the most recent data available for any given area.  All data was created from a hydro-flattened DEM and underwent extensive QA/QC for accuracy.  

Contours (LiDAR) – Years 2015 to 2018
For isolated areas, NCTCOG has engineering grade contours created by a contracted vendor.  Data was derived from 0.5 Meter LiDAR data and includes hydrology and transportation break-lines.  Data meets or exceeds NMAS vertical accuracies for 2-foot (1.0’ RMSE).  

Contours 2007 (ACS)
In 2007, NCTCOG and TxDOT contracted with a vendor to develop a terrain surface along with contours for 17 North Texas counties.  The technology used to develop the terrain surface is called Auto-Correlated Surface (ACS).  ACS is a “single return” technology, as opposed to LIDAR which can have multiple returns for one location and the resulting data may not be as accurate as LiDAR, especially in heavily vegetated areas.  ACS derived contours are available at 2” resolution and are suitable for cartographic purposes.    

Contours 2001 (LiDAR)
In 2001, NCTCOG contracted with a vendor to create 2’ contours for Dallas, Denton, Collin, Tarrant and Rockwall Counties.  The dataset was created from 2001 LiDAR and is hydro-flattened.  The contours do not include transportation break-lines.  

LiDAR .5 Meter (LAS)- Years 2015 to 2020
Since 2015, NCTCOG has contracted with a vendor to collect LiDAR at a density sufficient to support a nominal pulse spacing of 0.5 meters or less (i.e., with no less than 4 or more points per square meter).  NCTCOG LiDAR, which includes hydrologic break-lines, includes the following classifications: buildings (98%), bare earth, vegetation and more.  Each year’s LiDAR area is dependent upon the entities that buy into the project during the pre-flight period.

LiDAR Bare Earth (XYZ Text File) – 2001
In 2001 NCTCOG contracted with a  vendor to collect LiDAR for Dallas, Tarrant, Denton, Collin & Rockwall counties.  The bare earth version of the data is available in ASCII text files with elevation details included.  

Planimetrics - Year 2007
In 2007, NCTCOG contracted with a vendor to digitize building footprints, paved road edges, parking lots, bridges and sidewalk centerlines for a large portion of the North Texas region.  Data layers were stereo compiled using the 2007 6” orthophotography and are available in GIS  and CAD formats.