2013 South Carolina DNR Lidar: Beaufort County

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 the 2013 lidar project covering Beaufort County, South Carolina.

Breaklines in zipped geodatabase format as delivered. These have not been checked for accuracy by NOAA.

Project report produced by Dewberry (prime contractor)

Breaklines in GeoPackage format created from the GeoDatabase version using ogr2ogr.

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.

Data for the South Carolina Dept of Natural Resources project was acquired by Laser Mapping Specialist, Inc. (LMSI)

The project area included approximately 785 contiguous square miles for Beaufort County, South Carolina.

The data was delivered in the South Carolina State Plane (International Feet) coordinate system, horizontal datum NAD83 (NSRS 2007), vertical datum NAVD88, Geoid 09, Feet.

Lidar ground points for each flightline generated by an automatic classification routine are used.

LiDAR sensor data were collected with the Optech ALTM3100EA LiDAR system. No imagery was requested or delivered.

Deliverables for the project included a raw (unclassified) calibrated LiDAR point cloud, survey control, and a final control report.

Overall the LiDAR data products collected by LMSI meet or exceed the requirements set out in the Statement of Work.

The quality control requirements of LMSIs quality management program were adhered to throughout the acquisition stage of this project to ensure product quality.

LIDAR acquisition began on March 6, 2013 (julian day 065) and was completed on April 20, 2013 (julian day 079). A total of 16 survey missions were flown to complete the project.

The flight plan was flown as planned with no modifications. There were no unusual occurrences during the acquisition and the sensor performed within specifications. There were 203 flight lines required to complete the project.

Project coverage was checked on site with no data gaps except for water features.

Two base stations were utilized. The base station in the north west portion of the project was named G7_203. The base station on the central portion of the project was named GG.

Thirty (30) static points were surveyed at various locations throughout the project to be utilized for quality control and adjustment of the LiDAR data. All airborne trajectories were very high quality with forward/reverse separation between 2cm-5cm.

All equipment performed within specifications with no unusual occurances or anamolies. All data was of a very high quality and the project was executed as planned.

Dewberry utilizes a variety of software suites for inventory management, classification, and data processing. All LiDAR related processes begin by importing the data into the GeoCue task management software. The swath data is tiled according to project specifications (5000 ft x 5000 ft). The tiled data is then opened in Terrascan where Dewberry uses proprietary ground classification routines to remove any non-ground points and generate an accurate ground surface. Before the actual ground routine is run points with scan angles greater than plus or minus 18 degrees are classified to class 11, withheld. Due to these higher scan angles these points have the potential to introduce issues into the ground and are therefore not used in the final ground surface. The ground routine consists of three main parameters (building size, iteration angle, and iteration distance); by adjusting these parameters and running several iterations of this routine an initial ground surface is developed. The building size parameter sets a roaming window size. Each tile is loaded with neighboring points from adjacent tiles and the routine classifies the data section by section based on this roaming window size. The second most important parameter is the maximum terrain angle, which sets the highest allowed terrain angle within the model. Once the ground routine has been completed a manual quality control routine is done using hillshades, cross-sections, and profiles within the Terrasolid software suite. After this QC step, a peer review and supervisor manual inspection is completed on a percentage of the classified tiles based on the project size and variability of the terrain. After the ground classification corrections were completed, the dataset was processed through a water classification routine that utilizes breaklines compiled by Dewberry to automatically classify hydrographic features. The water classification routine selects ground points within the breakline polygons and automatically classifies them as class 9, water. During this water classification routine, points that are within 1 foot of the hydrographic features are moved to class 10, an ignored ground due to breakline proximity.

The fully classified dataset is then processed through Dewberry's comprehensive quality control program.

The data was classified as follows:

Class 1 = Unclassified. This class includes vegetation, buildings, noise etc.

Class 2 = Ground

Class 7 = Noise

Class 8 = Model Key Points

Class 9 = Water

Class 10 = Ignored

Class 11 = Withheld Points

Class 13 = Bridges and Culverts

The LAS header information was verified to contain the following:

Class (Integer)

Adjusted GPS Time (0.000001 seconds)

Easting (0.001 ft)

Northing (0.001 ft)

Elevation (0.001 ft)

Echo Number (Integer 1 to 4)

Echo (Integer 1 to 4)

Intensity (8 bit integer)

Flight Line (Integer)

Scan Angle (Integer degree)

The NOAA Office for Coastal Management (OCM) received the files in LAZ format from the South Carolina Department of Natural Resources (SCDNR) via a HDD. The files contained lidar elevation and intensity measurements. The data were in State Plane Zone 3900, NAVD88 (orthometric) heights in feet. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. The data were converted from State Plane coordinates to geographic coordinates.

2. The data were converted from NAVD88 (orthometric) heights in meters to GRS80 (ellipsoid) heights in meters using Geoid 09.

3. Classes 11 and 13 were reclassified to 15 to 17 respectively.

4. Erroneous elevations were removed.