2006 MDEQ Camp Shelby, MS Lidar Survey

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This graphic shows the lidar coverage for the Camp Shelby area in Mississippi collected in 2006.

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MGI requested the collection of lidar data over Camp

Shelby, MS. In response EarthData acquired the data

from March 21 to April 12, 2006 using its aircraft with tail

number N62912. Lidar data was captured using an ALS50

lidar system, including an inertial measuring unit (IMU) and

a dual frequency GPS receiver. An additional GPS

receiver was in constant operation over a National

Geodetic Survey published point by EarthData at

Hattiesburg- Bobby L. Chain Municipal Airport which was

later tied into a local network by Waggoner Engineering,

Inc. During the data acquisition, the receivers collected

phase data at an epoch rate of 1 Hz. The solution from

Camp Shelby, MS was found to be of high integrity and

met the accuracy requirements for the project. These

accuracy checks also verified that the data meets the

guidelines outlined in FEMA's Guidelines.

| Source Geospatial Form: model | Type of Source Media: DVD

Waggoner Engineering, Inc., under contract to EarthData

successfully established ground control for Camp Shelby,

MS. A total of 36 ground control points in Camp Shelby,

MS were acquired. GPS was used to establish the control

network. The horizontal datum was the North American

Datum of 1983 (NAD83). The vertical datum was the North

American Vertical Datum of 1988 (NAVD88).

| 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

above ground 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

1. The technician performs calibrations on the data set.

2. 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 layers 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.

7. The final bare earth was written to an LAS 1.0 format and

also converted to ASCII.

8. The point cloud data were delivered in LAS 1.0 format.

EarthData utilizes a combination of proprietary and COTS

processes to generate intensity images from the lidar

data. Intensity images are generated from the full points

cloud (minus noise points) and the pixel width is typically

matched to the post spacing of the lidar data to achieve

the best resolution. The following steps are used to

1. Lidar point cloud is tiled to the deliverable tile layout.

2. All noise points, spikes, and wells are deleted out of the

tiles.

3. An EarthData proprietary piece of software, EEBN2TIF

is then used to process out the intensity values of the lidar.

At this point, the pixel size is selected based on best fit or

to match the client specification if noted in the SOW.

4. The software then generates TIF and TFW files for each

tile.

5. ArcView is used to review and QC the tiles before

delivery.

6. The lidar intensity data were delivered in TIF format.

The NOAA Office for Coastal Management (OCM) received topographic files in .LAZ format. The files contained

lidar elevation and intensity measurements. The data were received in Mississippi State Plane East (2301, feet) and NAVD88

vertical datum (feet). OCM performed the following processing for data storage and Digital Coast

provisioning purposes:

1. The topographic laz files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid09.

2. The topographic laz files were transformed from MS-SP 2301 to a Geographic Coordinate system (NAD83).

3. The topographic laz files were cleaned of high (460 m) and low (0 m) error points and variable length records (vlr) were removed.

4. The topographic las files' horizontal units were converted from feet to decimal degrees.