2007 South Carolina DNR Lidar: Dorchester County

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This graphic shows the lidar coverage for the 2007 lidar project covering Dorchester County, South Carolina.

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.

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The ABGPS, IMU, and raw Leica ALS-50 LiDAR data are integrated into the LEICA ALS post processor software. The resultant file is in a LAS binary file format. The LAS file version 1.1 formats can be easily transferred from one file format to another. It is a binary file format that maintains information specific to the LiDAR data (return#, intensity value, xyz, etc.). The resultant points are produced in the geodetic coordinates referenced to the NAD83 horizontal datum and GRS80 vertical datum. The date and time for each flight line can be determined using the Julian date and time. The Julian date is a continuous count of days and fractions since noon Universal Time on January 1, 4713 BCE on the Julian calendar.

The unedited data are classified to facilitate the application of the appropriate feature extraction filters. A combination of proprietary filters is applied as appropriate for the production of bare earth digital terrain models (dtms). Interactive editing methods are applied to those areas where it is inappropriate or impossible to use the feature extraction filters, based upon the design criteria and/or limitations of the relevant filters. These same feature extraction filters are used to produce elevation height surfaces. The LiDAR mass points were delivered in American Society for Photogrammetry and Remote Sensing LAS 1.1 format.

Conversion from Geodetic coordinates NAD83 into State Plane coordinates (International Feet) NAD83 and conversion from ellipsoid heights (meters) into orthometric heights (U.S. Survey Feet).

Sanborn used GeoCue software to develop LiDAR stereo models. The raster resolution was 1.0 m.

LiDAR intensity stereo pairs were viewed in 3-D stereo using softcopy photogrammetric software; the breaklines were stereo-compiled in accordance with the Data Dictionary. The LiDARgrammetry was performed under the direct supervision of an ASPRS Certified Photogrammetrist. The breaklines conform to data format requirements outlined by the S.C. Dept. of Natural Resources project specifications.

Vector 3D breaklines were loaded in an ESRI file geodatabase; topology rules were validated to ensure that breaklines do not intersect or overlap.

Terrain population procedure: (1) Use ArcGIS "LAS to Multipoint" tool to output class 2 (2 and 8 for South Carolina) points to shapefile (2) Load multipoint shapefile features to geodatabase class (3) Make new terrain, use all appropriate feature classes to enforce the terrain a.HYDROGRAPHIC b.ROADBREAKLINE c.SOFTFEATURES d.ISLAND e.WATERBODY (4)Build terrain

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 meters. 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. Erroneous elevations were removed.