2014 Lidar DEM: St. Charles Parish (LA)

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This graphic shows the lidar footprint for the 2014 St. Charles Parish, LA project.

Date that the source FGDC record was last modified.

Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

Partial upload of Positional Accuracy fields only.

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Airborne Lidar and processing to seamless tiles | Source Geospatial Form: vector digital data | Type of Source Media: digital data files

All products were reviewed and approved by ASPRS Certified Photogrammetrist, Ken Comeaux.

DATA ACQUISITION: - Ground Control Survey: All lidar control and check points were collected by Precision Aerial Reconnaissance field crews by means of Real time VRS with a Trimble R10 receiver with internal antennas and using a TSC3 data collector. Trimble Business Center (TBC) software was used to process collected field data against a network of established NGS control. Each control or check point was occupied for a duration of at least 3 minutes. LiDAR check points were collected in the following ground classification categories: Bare Ground, Marsh, Tall Grass and Urban. In addition, a sampling of vertical LiDAR control points was collected in areas of Bare Ground. The LiDAR check and control points were also collected using VRS-RTK techniques. - LiDAR Acquisition: The LiDAR data was collected using a Leica ALS70CM sensor between 15-Feb-2014 and 30-Mar-2014 at an altitude of 4,500 feet AMT with a planned average point density of 9.1 points per square meter to support the generation of 2' contours meeting FEMA specifications for Aerial Mapping and Surveying to Support 2-foot contours. The LiDAR collection was supported by ground base stations.

LIDAR PROCESSING: - LiDAR Calibration: Initial processing of the GPS and IMU data was performed using Leica IPAS TC. The SOL was generated and Leica ALS Post Processor software was used to generate georeferenced laser returns which were then processed in strip form allowing for the QC of the overlap between strips (lines). The data from each line were combined and automated classification routines run to determine the initial surface model. This initial surface model was then verified to the LiDAR test points. - LiDAR Classification: The calibrated LiDAR data was run through automated classification routines and then manually checked. The data was classified into the following classes: Unclassified (1), Ground (2), Medium Vegetation (4), Low point and noise (7), Water (9) and Overlap (12). - Breakline Collection: Breaklines were collected in a 3-D MicroStation/Terrasolid software environment. Breakline vertex elevations were established based on surrounding lidar point elevations. - DEM Creation: Terrasolid software was used to generate DEMs from a Triangulated Irregular Network (TIN) comprised of lidar points and 3-D hydro-enforcement breaklines.

The NOAA Office for Coastal Management (OCM) received 770 files in .adf format. The bare earth raster files were at a 2 ft grid spacing. The data were in LA State Plane South, Zone 1702 (NAD83 NA11) coordinates and NAVD88 elevations in feet. OCM did the following for Digital Coast storage and provisioning purposes:

1. Converted the .adf format files to .tif format using gdal_translate

2. Converted the files from vertical units of feet to meters using gdal_translate

3. Copied the raster files to database and https

Files were converted to cloud optimized geotiff format to support streaming and the vertical units were reverted to feet to match the horizontal units.