2007 Delaware Coastal Programs Lidar: Kent and New Castle Counties

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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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Data Collection:

Using a Leica Systems ALS50 Light Detection and Ranging (LiDAR) system, flight lines of standard density ground spacing of 1.4 meter and

1.0 meter (within the Wilmington Urban Area) data were collected over areas in Kent County, DE (approximately 800 square miles) and New

Castle County, DE. Multiple returns were recorded for each laser pulse along with an intensity value for each return.

The data acquisition occurred in 7 missions between March 31, 2007 and April 5, 2007. During the LIDAR campaign, the Sanborn field crew

conducted a GPS field survey to establish final coordinates of the ground base stations for final processing of the base-remote

GPS solutions.

Airborne GPS Processing:

Airborne GPS data were differentially processed and integrated with the post processed IMU data to derive a smoothed best estimate

of trajectory (SBET). The SBET was used to reduce the LiDAR slant range measurements to a raw reflective surface for each flight line.

The overlap between flight lines was removed to provide a homogeneous coverage, and the coverage was classified to extract a bare

earth digital elevation model (DEM).

Airborne GPS is differentially processed using the GrafNAV V7.50 software by Waypoint Consulting of Calgary, Alberta, Canada.

The PDOP and distance separation are as follows:

IMU data is processed using the PosPac V4.2 software by Applanix Corporation of Richmond Hill, Ontario, Canada.

The reflective surface is derived using the ALS Post Processor software by Leica Geosystems GIS & Mapping Division of Atlanta, Georgia.

The classification and quality control (QC) of LiDAR data is carried out using TerraScan software by Terrasolid Limited of Helsinki, Finland.

IMU data Processing:

IMU data provides information concerning roll, pitch and yaw of collection platform during collection event. IMU information allows

the pulse vector to be properly placed in 3D space allowing the distance from the aircraft reference point to be properly positioned

on the elevation model surface. IMU data is processed using the PosPac V4.2 software by Applanix Corporation of Richmond Hill, Ontario,

Canada.

Reflective Surface Generation:

The reflective surface is derived using the ALS Post Processor software by Leica Geosystems GIS & Mapping Division of Atlanta, Georgia.

LIDAR Point Classification

The classification and quality control (QC) of LiDAR data is carried out using TerraScan software by Terrasolid Limited of Helsinki,

Finland.

Output LAS Files

The product output of LiDAR data is carried out using TerraScan software by Terrasolid Limited of Helsinki, Finland. LAS Binary and

ArcGIS shapefiles were created. The shapefiles represented the bare earth product. All data were tiles to be consistent with the

statewide orthoimagery tile layout. Two sets of data were provided -- one in ft (vertical) and the other in meters (vertical).

Both had meters horizontal units.

The NOAA Office for Coastal Management (OCM) received files in LAS format. The files contained LiDAR intensity

and elevation measurements. OCM performed the following processing on the data to make it available within the Digital

Coast:

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

2. The data were converted from orthometric to ellipsoid heights using Geoid03.

3. The LAS header fields were sorted by latitude and updated.

4. The data were filtered to eliminate outliers.