Data Management Plan (Deprecated)

Product: These are LAZ compressed LAS LiDAR data as part of the required deliverables for the Lidar project. These lidar data are processed Classified LAS 1.4 files; used to create intensity images, 3D breaklines and hydro-flattened DEMs as necessary. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 2 meter (6 feet) hydro-flattened Raster DEM data product consists of processed topographic elevation point data derived from multiple return light detection and ranging (lidar) measurements. The lidar data was planned and acquired at 2 points per square meter for the project boundary identified in the shapefile provided NOAA on January 6th, 2017. The developed lidar derivatives are hydro-flattened DEMs.

Geographic Extent: The Atlantic Group, LLC (Atlantic) has successfully completed lidar acquisition for the Georgia 9 County Lidar area of interest (AOI). Lidar for this AOI was acquired in sixteen (16) flight missions completed between November 25th, 2017 and January 24th, 2018. The project area encompasses 1,550,933 acres, 6,276 square kilometers or 2,440 square miles in Georgia covering the Middle Chattahoochee Walter‐F Watershed including Taylor, Chattahoochee, Stewart, Webster, Quitman, Randolph, and Clay Counties; Upper Flint Watershed including portions of Pike, Lamer and Upson Counties; and a portion of Lee County in the Kinchafoonee‐Muckalee Watershed.

In addition to these lidar point data, the bare earth Digital Elevation Models (DEM) created from the lidar point data, and the hydro breaklines are also available. These data are available for download at the links provided in the URL section of this metadata record.

Process Steps:

• 2017-10-27 00:00:00 - Survey Data Acqisition: Project Introduction: Platinum Geomatics, LLC entered into contract with the Atlantic Group on March 1st, 2017 to perform geodetic control surveying for the calibration and quality control of 9 counties of LiDAR in South Georgia. This is a report of the methodology used and calculated accuracy of the survey performed by Platinum Geomatics, LLC. Procedures Used: The Trimble Virtual Reference System (VRS) was employed to obtain real-time GNSS corrections for most of the points. When real-time corrections could not be obtained, due to either poor cellular connection or aerial obstructions affecting the geometric dilution of precision (GDOP), a static GNSS session was run and receiver independent exchange format (RINEX) files of the navigated position were downloaded from the VRS. Static GNSS baselines were post-processed using Trimble Business Center (TBC) software. Real-time VRS observations consisted of a minimum of 180 1-second epochs and point tolerances were set to record within 0.049’ horizontal and 0.066’ vertical accuracies. Equipment Used: Trimble R-7, R-8, and R-10 dual frequency GNSS receivers were used. Project Datum: Individual point coordinates were reported to NAD83 (2011) Georgia West zone. Coordinates and elevations were reported in US Survey Feet. Reported Elevations are relative to NAVD88 as derived from Geoid 12B. Point Description Quantity Non-vegetated LiDAR Quality Control 50, Vegetated LiDAR Quality Control 37, and LiDAR Calibration 26
• 2017-11-25 00:00:00 - Flight Acquisition: Atlantic acquired one hundred eighty-one (181) passes of the AOI as a series of perpendicular and/or adjacent flight-lines. Differential GNSS unit in aircraft recorded sample positions at 2 Hz or more frequency. Lidar data was only acquired when a minimum of 6 satellites were in view. Atlantic lidar sensors are calibrated at a designated site located at the Fayetteville Municipal Airport (FYM) in Fayetteville, TN and are periodically checked and adjusted to minimize corrections at project sites. Atlantic operated a Cessna 210TL (N732JE) and Partenavia P68 (N775MW) outfitted with a Leica ALS70-HP lidar system during the collection of the project area. Data acquisition was completed between 24th November 2017 and 24th January 2018.
• 2019-07-02 00:00:00 - Lidar Pre-processing: Atlantic used a combination of Waypoint and Leica software products to extract the lidar swath data from the raw flight records. Waypoint Inertial Explorer is used to extract the raw IPAS ABGPS/IMU data, which is further processed in combination with controlled base stations to provide the final Smoothed Best Estimate Trajectory (SBET) for each mission. The SBET’s are combined with the raw laser scan files to export the (*.las) formatted swath point clouds.
• 2019-07-02 00:00:00 - LiDAR ranging data were initially calibrated using previous best parameters for this instrument and aircraft. Using a combination of GeoCue, and TerraSolid’s TerraScan and TerraMatch the overlapping swath point clouds are corrected for any orientation or linear deviations to obtain the best fit swath-to-swath calibration. Relative calibration was evaluated using advanced plane-matching analysis and parameter corrections derived. This process was repeated interactively until residual errors between overlapping swaths, across all project missions, was reduced to 2 cm or less. A final analysis of the calibrated LiDAR is preformed using a TerraMatch Tie Line report for an overall statistical model of the project area. Upon completion of the data calibration, Atlantic runs a complete set of Delta-Z (dZ) ortho images. A user-defined color ramp is applied depicting the offsets between overlapping swaths based on project specifications. The dZ orthos provide an opportunity to review the data calibration in a qualitative manner. Atlantic assigns green to all offset values that fall below the required interswath accuracy RMSDz requirement of the project. A yellow color is assigned for offsets that fall between the RMSDz value and 1.5x of that value. Finally, red values are assigned to all values that fall beyond 1.5x of the RMSDz requirements of the project. The calibrated point cloud data from the laser sensor was merged to produce processed (*.las) file(s) including but not limited to 3D position, intensity, and time-stamp. A filtering methodology was utilized to produce a multi-return surface elevation model dataset with bare-earth conditions. GeoCue, TerraScan, and TerraModel software was used for the initial batch processing and manual editing of the (*.las) point clouds. Atlantic utilized collected breakline data to perform classification for classes’ 9-Water and 10-Ignored Ground in LP360.
• 2019-09-10 00:00:00 - The NOAA Office for Coastal Management (OCM) received a total of 3052 laz files (in four blocks) from Tetra Tech. The lidar data had elevation and intensity measurements. The data were in State Plane Georgia West (NAD83 2011) coordinates (US Survey Feet) and NAVD88 (Geoid12B) elevations in meters. The data were classified as: 1-Unclassified, 2-Ground, 7-Low Noise, 9-Water, 10-Ignored Ground due to breakline proximity, 17-Bridge Decks, 18-High Noise . OCM processed all classifications of points to the Digital Coast Data Access Viewer (DAV). Classes available on the DAV are: 1, 2, 7, 9, 10, 17, 18. OCM performed the following processing on the data for Digital Coast storage and provisioning purposes: 1. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges. 2. Internal OCM scripts were run on the laz files to convert from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid 12B model, to convert from State Plane Georgia West (NAD83 2011) coordinates in US survey feet to geographic coordinates, to assign the geokeys, to sort the data by gps time, and zip the data to database and to http.

Data is available online for bulk and custom downloads.

Data is backed up to tape and to cloud storage.