2004 Connecticut Coastline Lidar Mapping

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

Simple download of data files.

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.

Minimizes horizontal error caused by IMU mis-alignment by checking over known range and by comparing positional

results from adjacent flight lines to compute error adjustment function.

| Type of Source Media: Validation Report

Raw spatial elevation information | Type of Source Media: DVD-ROM

Data Collection: Using a LH Systems ALS50 Light Detection and Ranging (LiDAR) system, 41 flight lines of high

density (submeter ground sample distance) data were collected over areas in coastal Connecticut (approximately 300 square kilometers).

Two returns were recorded for each laser pulse along with an intensity value for each return. The data acquisition occurred in one

(1) mission on October 8, 2004. Three (3) airborne global positioning system (GPS) base stations were used to support the LiDAR data

acquisition: Moriches 1 continuously operating reference station (CORS) ARP, NGS point P36, and one station Woolpert located using

static GPS positioning methods, Madison CP. In addition, twenty-two control points were surveyed through fast-static GPS methods

to support the final accuracy analysis and tied into the National Geodetic Survey (NGS) points Moriches CORS and P36.

Airborne GPS Processing: Airborne GPS data was 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 V4.10 software by Waypoint Consulting of Calgary, Alberta, Canada. The PDOP and distance separation is as

follows: P36: Maximum PDOP = 3.58 (maximum) Average Distance Separation: 17 km Madison CP: Maximum PDOP = 3.58 (maximum) Average

Distance Separation: 19 km 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 a combination of proprietary

software and TerraScan software by Terrasolid Limited of Helsinki, Finland. Two (2) coverages were delivered in the LAS file

format: bare-earth and above ground features.

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

a combination of proprietary software and TerraScan software by Terrasolid Limited of Helsinki, Finland.

Output LAS Files Random LIDAR points maintained in UTM coordinate system converted to Geographic projection

with units of Decimal Degrees

Transfer to delivery media: Data is transferred from hard-disk to DVD delivery media using a Primera Bravo

DVD/CDROM disc publishing hardware.

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 LiDAR Data Retrieval

Tool (LDART):

1. The las files were converted from State Plane coordinates to Geographic coordinates.

2. The las header fields were sorted by latitude and updated.

For data management purposes, the Office for Coastal Management (OCM) converted the data from NAVD88 heights to

ellipsoid heights using Geoid 03.