2004 Saginaw Bay, Lake Huron, Michigan Coastline LiDAR

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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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Twenty-four (24) 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

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 April 27 2004 through May 4, 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

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. 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.