Data Management Plan

Phase two will consist of post processing of the data collected. Aeroquest Optimal, Inc. shall

process the digital elevation data from a precision airborne (LIDAR) survey within the entire

project area. The proposed project area is approximately 6.3 million acres. The purpose of the

survey is to obtain measurements of the bare ground surface, as well as top surface feature

elevation data for providing geometry input to USACE hydraulic modeling program.

This project for USACE, Vicksburg District was to provide digital orthophotography using DMC imagery

for approximately 4,120 square miles located in NW Mississippi at a 2-foot pixel resolution.

Original contact information:

Contact Name: Elijah C. Hunt

Contact Org: U.S. Army Corps of Engineers, Vicksburg District

Phone: (601) 631-7040

Email: elijah.c.hunt@us.army.mil

Process Steps:

• 2010-03-05 00:00:00 - During acquisition, two base stations were used to support the precise positioning and orientation of the LiDAR sensor head. At times an additional base station set at the Oxford Airport was used as a back-up. The base stations were positioned so that the aircraft would be no further than 20-miles from a single base station at any time during the flight and were placed on the control points established by Maptech during the ground control phase of the project. The LiDAR acquisition commenced on December 17, 2009 and was completed on March 5, 2010. Initial processing of the LiDAR data determined that reflights were necessary; in part because of sensor or base station malfunctions. The reflights occurred between June 27, 2010 and July 9, 2010. To achieve better penetration of the vegetation during the reflights, two passes were conducted over the reflight area; one in each direction. Detailed flight information and flight logs can be found in the separate Flight Report submitted with the project.
• For redundancy and accuracy purposes, the airborne GPS data were processed from two base stations using POSGPS from Applanix, Inc. The agreement between a minimum of two solutions checked or combined between a minimum of two stations was better than 10 cm in each of X, Y, and Z. These trajectories were used in the processing of the inertial data. The inertial data were processed using POSProc from Applanix, Inc. This software produces an SBET ("smooth best estimate of trajectory") using the GPS trajectory from POSGPS and the roll, pitch and heading information recorded by the POS (Position Orientation System). DASHMap uses the SBET to generate a set of data points for each laser return in the LAS file format. Each data point is assigned an echo value so it can be segregated based on the first and last pulse information. This project's data were processed in strip form, meaning each flight line was processed independently. Processing the lines individually provides the data analyst with the ability to QC the overlap between lines. Each strip was then imported into a project using TerraScan (Terrasolid, Ltd.) and the project management tool GeoCue (GeoCue Corp.). By creating a project the various flightlines are combined while breaking the dataset as a whole into manageable pieces. This process also converts the dataset from the geographic coordinate system (NAD83) to the State Plane Coordinate System (NAD83), Mississippi West, Feet, and utilizing standard ESRI transformations. The ellipsoid height values were converted to NAVD88, Feet, orthometric values using Geoid03, provided by NGS. Individual lines were then checked against adjacent lines and intersecting control lines to ensure a cohesive dataset. The data from each line were then combined and LiDAR intensity images were produced to visually check the horizontal positioning of the LiDAR data. Stereo pairs were generated from the LiDAR intensity data using Geocue and LiDAR1CuePac (Geocue Corp.). LiDARgrammetry was then utilized to collect breaklines where necessary along hydro features to support the contour generation. These breaklines were collected as a 3D element in the MicroStation (Bentley Systems, Inc.) environment utilizing ISSD (Z/I Imaging). A Triangular Irregular Network (TIN) was generated using the final surface data. Contours were then created from the TIN utilizing TerraModeler (Terrasolid, Ltd.).
• 2013-12-20 00:00:00 - The NOAA Office for Coastal Management (OCM) received topographic files in text format from the Mississippi Department of Environmental Quality (MDEQ). The files contained lidar easting, northing and elevation. The data were received in Mississippi State Plane West 2302, NAD83 coordinates and were vertically referenced to NAVD88 using the Geoid03 model. The vertical and horizontal units of the data were feet. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The ASCII files were converted from txt format to las format using LASTools' txt2las 2. The LAS tiles were retiled to remove the buffer, then duplicate points were removed 3. The LAS tiles were then run through LASGround in order to extract surface classifications. 4. The las files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid03. 5. The las files' vertical units were converted from feet to meters, removing bad elevations. 6. The las files were converted from a Projected Coordinate System (MS SP West) to a Geographic Coordinate system (NAD83) 7. The las files' horizontal units were converted from feet to decimal degrees and converted to laz format.

This data can be obtained on-line at the following URL:

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2600

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