2011 USACE NCMP Topobathy Lidar: Gulf Coast (AL, LA, MS)

Create custom data files by choosing data area, product type, map projection, file format, datum, etc.

Simple download of data files.

This graphic shows the lidar coverage for barrier islands along the coasts of Alabama, Mississippi and Louisiana.

Link to custom download, from the Data Access Viewer (DAV), the raster Digital Elevation Model (DEM) data that were created from this lidar data set.

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.

Partial upload to move data access links to Distribution Info.

These data were collected using the CHARTS system. It is owned by the Naval Oceanographic Office and operated through contract. The system collects topographic lidar data at 10 kHz, bathymetric lidar data at 1 kHz and RGBimagery at 1Hz. A CASI-1500 hyperspectral line scanner is integrated with the system as well. Aircraft position, velocity and acceleration information are collected through a combination of Novatel and POS A/V 410 equipment.All raw data streams are transferred to the office for downloading and processing in SHOALS GCS software. Aircraft position data are processed using POSPac software and the results are combined with the lidar data to produce3-D positions for each lidar shot. Upon inspection and QA/QC in the software packages Fledermaus and PFM_ABE, anomalous data are flagged as invalid. PFM_ABE's charts2las module then converts all valid data from ellipsoid toorthometric heights based on the NGS' GEOID03 model and exports topographic and bathymetric data as a series of LAS files, one file per flight line. The format of the file is LAS version 1.2. Data are classified as 0(valid topographic data), 21 (valid topographic data acquired with the bathymetric sensor), 27 (invalid topographic and bathymetric data), 29 (valid bathymetric data).

The flightline LAS files are imported into GeoCue V7.0.3.5, which is a geospatial workflow production and management software tool employed by JALBTCX to perform and monitor production of data products. Upon import into GeoCue,the flightline LAS files are divided into a series of boxes, each of which are 1500 meters in length and width. A customized classification macro, built upon the TerraScan V11 module within Microstation V8i, classifies validtopographic data as ground points (2) and unclassified points (1). Upon completion the macro, the classification results undergo quality control and any misclassified points are manually edited. In areas of dense vegetation thebare earth ground points might be incorrectly classified due to the inability of the laser to penetrate the canopy and reach the bare ground. In these areas, JALBTCX defaults to the algorithms ground surface instead of manuallyreclassifying those points. The final classification results are comprised of individual lidar points with classifications of valid ground (2), valid unclassified (1), and invalid low points (7). They are partitioned into aseries of 5km delivery boxes, one Classified LAS file per box. The format of the file is LAS version 1.2. Data are classified as 1 (valid non-ground topographic data), 2 (valid ground topographic data), 7 ( invalid topographiclow points), 21 (valid topographic data acquired with the bathymetric sensor), 27 (invalid topographic and bathymetric data), 29 (valid bathymetric data). Horizontal positions, provided in decimal degrees of latitude and longitude, are referenced to the North American Datum of 1983 (NAD83). Vertical positions are referenced to the NAD83 ellipsoid and provided in meters. The National Geodetic Survey's (NGS) GEOID03 model is used to transform the vertical positions from ellipsoid to orthometric heights referenced to the North American Vertical Datum of 1988 (NAVD88).

The NOAA Office for Coastal Management (OCM) received the topographic las files on hard drive from USACE. The files contained lidar elevation and intensity measurements. The data were received in Geographic, NAD83 coordinates and were vertically referenced to NAVD88 using the Geoid03 model. The vertical units of the data were meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. The topographic las files were converted to laz v1.2 using LAStools' laszip software.

2. The GPS Week Time information was converted to Adjusted Standard GPS Time using LAStools' las2las software.

3. The topographic laz files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid03.

Points with classes 14 and 17 (approximately 50 total points) were reclassed to class 1 (unclassified).