2005 Hancock and Jackson Counties, Mississippi LiDAR

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EarthData Aviation was contracted by EarthData International to collect ALS-50 Lidar data over Hancock and

Jackson Counties, Mississippi. The project site was flown on February 25 and March 1, 10, 11, and 12 using its aircraft with

tail number N2636P. Lidar data was captured using an ALS-50 Lidar system, including an inertial measuring unit (IMU) and a dual

frequency GPS receiver. Lidar was obtained at an altitude of 3,658 meters (12,000 feet) above mean terrain, at an average airspeed

of 145 knots. Sensor pulse rate was set at 29,900 Hz with a field of view of 45 degrees and a scan rate of 17 Hz. Average swath

width of the collected raw lines is 3,100 meters. Point spacing was 5 meters. Lidar data was recorded in conjunction with airborne

GPS and IMU; the stationary GPS receiver was positioned over a control point located at the airport. Recorded digital data was

shipped via external hard drive to the production facility for processing. During airborne data collection, an additional GPS

receiver was in constant operation over a published National Geodetic Survey (NGS) control point at KHSA (Stennis International)

Airport. The coordinate value for temporary control point STENNIS (BH2999) was determined by a network adjustment to CORS stations

MOB1 and NDBC, both of which were tied to the project control network. During the data acquisition, the 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: Firewire Drive

EarthData International under contract to the NOAA Office for Coastal Management collected, processed and delivered

lidar point cloud data for Hancock and Jackson counties in Mississippi.

| Source Geospatial Form: Diagram | Type of Source Media: Firewire drive

Kevin Chappell, of Terrasurv and under contract to EarthData International established at total of 40 survey

points within Jackson and Hancock Counties, MS. The survey was completed in two phases; the first phase consisted of 8 lidar control

points in southern Jackson County. The second phase consisted of 12 additional lidar control points in Jackson County and 20 new

lidar control points in Hancock County.

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

EarthData has developed a unique method for processing lidar data to identify and remove elevation points

falling on vegetation, buildings, and other aboveground structures. 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. The

following is a step-by-step breakdown of the process.

1. Using the lidar data set provided by EarthData, the technician performs calibrations on the data set.

2. Using the lidar data set provided by EarthData, the technician performed a visual inspection of the data to verify that the

flight lines overlap correctly. The technician also verified that there were no voids, and that the data covered the project limits.

The technician then selected a series of areas from the data set and inspected them where adjacent flight lines overlapped. These

overlapping areas were merged and a process which utilizes 3-D Analyst and EarthData's proprietary software was run to detect and

color code the differences in elevation values and profiles. The technician reviewed these plots and located the areas that

contained systematic errors or distortions that were introduced by the lidar sensor.

3. Systematic distortions highlighted in step 2 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 one type of land cover to another.

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 initial batch-processing run removed 95% of points falling on vegetation. The algorithm also removed the points that

fell on the edge of hard features such as structures, elevated roadways and bridges.

6. The operator interactively processed the data 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. Geo-referenced

images were 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.

6. The final DEM was written to an ESRI grid format (.flt).

7. The point cloud data were also delivered in LAS format.

8. Project data was clipped to a 500-meter buffer outside of the official project boundary.

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 UTM coordinates to Geographic coordinates.

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

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

elevations using Geoid 03.