2004 Maine Coastline LiDAR

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The project area was flown using EarthData Aviation's Piper Navajo aircraft with tail number 62912. LIDAR

data was captured using an ALS40 LIDAR system, including an inertial measuring unit (IMU) and a dual frequency GPS receiver.

The acquisition was flown during the period of May 5, 2004 through May 6 2004. One ground based GPS receiver was in constant

operation during each flight. During the data acquisition, all receivers collected phase data at an epoch rate of 1 Hz. All

GPS phase data was post processed with continuous kinematic survey techniques using "On the Fly" (OTF) integer ambiguity

resolution. The GPS data was processed with forward and reverse processing algorithms. The results from each process, using

the data collected at the airport, were combined to yield a single fixed integer phase differential solution of the aircraft

trajectory.

| Source Geospatial Form: Model | Type of Source Media: CD-ROM

Ten (10) ground control points were established by Terrasurv, Inc. using GPS for vertical and horizontal

coordinate values. Ground control references NAD83, NAVD88, Geoid99, in meters. An additional thirty (30) independent check

ground control points were acquired by Terrasurv, Inc. and provided directly to NOAA, OCM to support an independent analysis of

the accuracy of the Lidar data.

| Source Geospatial Form: Model | Type of Source Media: Electronic mail system

EarthData has developed a unique method for processing LIDAR data. The algorithms for filtering data were

utilized within EarthData's proprietary software and commercial software written by TerraSolid. This software suite of tools

provides efficient processing for small to large-scale projects and has been incorporated into ISO 9001 compliant production

work flows. POINT CLOUD The following is a step-by-step breakdown of the process utilized to produce the variably-spaced point

cloud surface data set.

1. Processing of the LIDAR data begins with refinement of the initial boresight alignment parameters provided by EarthData

Aviation in the LITES configuration file delivered with the raw data. The technician also verifies that there are no voids,

and that the data covers the entire project area. Calibration is accomplished using the tri-directional flight lines over

the project airport, which is generally flat and free of major obstructions, trees or brush. Two overlapping bi-directional

lines are flown along the length of the runway, and the cross flight line is perpendicular to both. All three lines are examined

to ensure that they agree, within expected system tolerances, in the overlapping areas. The technician will review flight lines

and locate the areas that contained systematic errors or distortions that were introduced by the LIDAR sensor.

2. Systematic distortions highlighted in step 1 were removed and the data was re-inspected. Corrections and adjustments can

involve the application of angular deflection or compensation for curvature of the ground surface that can be introduced by

crossing from on type of land cover to another.

3. All flight lines are processed with the refined calibration parameters obtained thru steps 1 and 2. All flight line are

examined to ensure that they agree, within expected system tolerances, in the overlapping areas (side lap).

4. The LIDAR data for each flight line was trimmed in batch for the removal of the overlap areas between flight lines.

The data was checked against a control network to ensure that vertical requirements were maintained. Conversion to the

client-specified datum and projections were then completed. The LIDAR flight line data sets were then segmented into adjoining

tiles for batch processing and data management.

5. The data was then edited for Blunder removal.

6. The data was processed interactively by the operator using LIDAR editing tools. During this final phase the operator generated

a TIN based on a desired thematic layer to evaluate the automated classification performed in step 5. This allowed the operator

to quickly re-classify points from one layer to another and recreate the TIN surface to see the effects of edits. The use of

geo-referenced images was toggled on or off to aid the operator in identifying problem areas. The data was also examined with an

automated profiling tool to aid the operator in the reclassification.

7. Orthometric heights were converted using the Geoid 03 undulation model.

8. The data was separated into (1) variably-spaced point cloud in LAS files. The files were written to PC readable CD-ROM.

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 data were projected from UTM to geographic decimal degrees using the General Cartographic Transformation Package.

2. The las files were sorted by latitude and the las header fields were completed.

For data management purposes, the Office for Coastal Management converted the data from NAVD88 elevations to

ellipsoid elevations using Geoid 03.