Lidar Data Release For Parts of North & Central Texas

A sample of collected Lidar data

The Texas Natural Resources Information System (TNRIS) is pleased to announce the release of newly acquired high resolution Lidar data for 3,090 square miles of Johnson, Ellis, Hill, McLennan, Limestone, Navarro and Henderson Counties in North Texas as well as 1,452 square miles of Wilson and Karnes Counties in Central Texas. Aerial collection took place from January to March 2013 during the leaf-off season. Gorrondona & Associates teamed with McKim & Creed and Williams Aerial Mapping to perform data acquisition/processing while URS Corporation provided third-party quality assurance and quality control (QA/QC).

This project was administered by the TNRIS Strategic Mapping Program (StratMap) and the data were procured through the Council on Competitive Government’s (CCG) High Priority Imagery and Datasets (HPIDS) contract. Funding was provided by the U.S. Department of Agriculture Natural Resources Conservation Service (NRCS), the Texas Commission on Environmental Quality (TCEQ), the San Antonio River Authority (SARA) and the Texas Water Development Board (TWDB).

map of lidar coverage Click for Full Preview
AOI Central image Click for Full Preview

Data Access

Lidar data and the associated geospatial products listed above are available for cost of reproduction through TNRIS.

Products

  • Classified all-return Lidar DO4Q tiles (1/64th of USGS Quad) in LAS 1.2 format
  • Bare-earth digital elevation model (DEM) in USGS .dem format (1-meter)
  • Lidar intensity images in GeoTIFF format (1-meter)
  • Hydro-flattening breaklines in SHP
  • File-level FGDC metadata in XML

Product Specification

  • Vertical accuracy (RMSEz) tested ~ 7 cm (2.7 in) in the North Texas area of interest and tested 14 cm (5.5 in) in the Central Texas area of interest. The tested accuracy in both areas exceeds the project specification of 15 cm.
  • Average first-return point density is slightly over 4 points per square meter (ppsm) in both areas of interest, meeting the 4 ppsm state standard identified in the project specification.
  • Point data are classified according to the following American Society for Photogrammetry and Remote Sensing (ASPRS) class schema:
    • Class 1: Unclassified
    • Class 2: Ground
    • Class 4: Vegetation
    • Class 6: Buildings
    • Class 7. Low Point (noise)
    • Class 9. Water
    • Class 13. Bridges and Culverts
  • Horizontal projection is UTM NAD83 (NSRS 2007) Zones 14 & 15
  • Vertical projection is NAVD88 Geoid 12A
  • Units are in meters denoting orthometric heights
  • Structure for data listed above shall conform to 1/64th USGS 7.5-minute quadrangle
  • Quarter-quarter-quarter quadrangle (DOQQQQ, or DO4Q)
    A diagram of the DOQQ grid system

Sample Images

A sample of collected LiDAR data

A sample of collected LiDAR data

A sample of collected LiDAR data

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