57266
2017 GA DNR Lidar DEM: Middle Chattahoochee - Walter F Watershed
ga2017_chattahoochee_dem_m8840
Data Set
Published / External
49404
DEMs - partner (no harvest)
Project
Completed
2019-09-11
Product: These are Digital Elevation Model (DEM) data as part of the required deliverables for the Lidar project. 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 bare earth Digital Elevation Model (DEM) data, the lidar point data that these DEM data were created from, 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.
The data produced is intended to support local hydrologists and watershed managers in their decision-making processes.
Raster File Type = TIFF
Bit Depth/Pixel Type = 32-bit float
Raster Cell Size = 2 meter (6 feet)
Interpolation or Resampling Technique = Bi-linear Interpolation
Required Vertical Accuracy = 24.5 cm nva for base spec 1.2
Theme
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION
Theme
ISO 19115 Topic Category
elevation
Spatial
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > GEORGIA
Spatial
Global Change Master Directory (GCMD) Location Keywords
VERTICAL LOCATION > LAND SURFACE
Instrument
Global Change Master Directory (GCMD) Instrument Keywords
LIDAR > Light Detection and Ranging
Platform
Global Change Master Directory (GCMD) Platform Keywords
Airplane > Airplane
Platform
Global Change Master Directory (GCMD) Platform Keywords
DEM > Digital Elevation Model
Theme
ISO 19115 Topic Category
Digital Terrain Model
Theme
ISO 19115 Topic Category
LAS
Theme
ISO 19115 Topic Category
LiDAR
Spatial
Chattahoochee County
Spatial
Clay County
Spatial
Kinchafoonee-Muckalee Watershed
Spatial
Lamar County
Spatial
Lee County
Spatial
Middle Chattahoochee Walter-F Watershed
Spatial
Pike County
Spatial
Quitman County
Spatial
Randolph County
Spatial
Stewart County
Spatial
Taylor County
Spatial
Upper Flint Watershed
Spatial
Upson County
Spatial
Webster County
Office for Coastal Management
Charleston
SC
Data Set
Elevation
As Needed
Model (Digital)
The data represented are the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of data collection. As such, it is only valid for its intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than its intended purpose.
Any conclusions drawn from the analysis of this information are not the responsibility of the GA DNR, NOAA, the Office for Coastal Management, or its partners.
The Atlantic Group, LLC, GA DNR
Data Steward
2019
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
Distributor
2019
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
Metadata Contact
2019
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
Point of Contact
2019
Organization
NOAA Office for Coastal Management
NOAA/OCM
coastal.info@noaa.gov
2234 South Hobson Ave
Charleston
SC
29405-2413
(843) 740-1202
https://coast.noaa.gov
NOAA Office for Coastal Management Home Page
Online Resource
Ground Condition
-85.142949
-84.000872
33.190413
31.484983
Range
2017-11-25
2018-01-24
Vertical
EPSG:5703
NAVD88 height
North American Vertical Datum 1988
1
Gravity-related height
H
metre
up
Unclassified
Data is available online for bulk and custom downloads.
None
Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.
2019-08-22
https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=8840
2019
Organization
NOAA Office for Coastal Management
Customized Download
Create custom data files by choosing data area, map projection, file format, etc. A new metadata will be produced to reflect your request using this record as a base.
Zip
Zip
2019-08-22
https://coast.noaa.gov/htdata/raster2/elevation/GA_Chattahoochee_DEM_2017_8840
2019
Organization
NOAA Office for Coastal Management
Bulk Download
Bulk download of data files in the original coordinate system.
GeoTIFF
GeoTIFF
https://coast.noaa.gov/htdata/lidar3_z/geoid12b/data/8839/supplemental/ga2017_chattahoochee_m8839.kmz
Browse Graphic
Browse Graphic
KML
This graphic displays the footprint for this lidar data set.
https://coast.noaa.gov/
NOAA's Office for Coastal Management (OCM) website
Online Resource
HTML
Information on the NOAA Office for Coastal Management (OCM)
https://coast.noaa.gov/dataviewer/
NOAA's Office for Coastal Management (OCM) Data Access Viewer (DAV)
Online Resource
HTML
The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.
https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=8839
Online Resource
Link to custom download the lidar point data from which these raster Digital Elevation Model (DEM) data were created.
https://coast.noaa.gov/htdata/lidar3_z/geoid12b/data/8839/breaklines/
Online Resource
Link to the hydro breaklines.
https://coast.noaa.gov/htdata/lidar3_z/geoid12b/data/8839/supplemental/17019_Aerial_Lidar_Report.pdf
Data set report
Online Resource
PDF
Link to data set report
As described in Section 7.5 of the ASPRS Positional Accuracy Standards for Digital Geospatial Data the horizontal errors in lidar data are largely a function of GNSS positional error, INS angular error, and flying altitude. Therefore, lidar data collected with GNSS error of 8cm and the IMU error of 0.00427 degrees at an altitude of 1,957m; the expected radial horizontal positional error will be RMSEr = 43cm.
Atlantic established a total of fifty -two (52) check points for this project (29 NVA + 23 VVA). Point cloud data accuracy was tested against a Triangulated Irregular Network (TIN) constructed from lidar points in clear and open areas. A clear and open area can be characterized with respect to topographic and ground cover variation such that a minimum of 5 times the NPS exists with less than 1/3 of the RMSEZ deviation from a low-slope plane. Slopes that exceed 10 percent were avoided. Each land cover type representing 10 percent or more of the total project area were tested and reported with a VVA. In land cover categories other than dense urban areas, the tested points did not have obstructions 45 degrees above the horizon to ensure a sufficient TIN surface. The VVA value is provided as a target. It is understood that in areas of dense vegetation, swamps, or extremely difficult terrain, this value may be exceeded. The NVA value is a requirement that must be met, regardless of any allowed “busts” in the VVA(s) for individual land cover types within the project. Checkpoints for each assessment (NVA and VVA) are required to be well-distributed throughout the land cover type, for the entire project area.
Below are the vertical accuracy reporting requirements for this project: Vertical Accuracy Reporting Requirements in Feet:
RMSEZ ≤ 0.328 ft (Non-Vegetated Swath, DEM)
NVA ≤ 0.643 ft 95% Confidence Level (Swath, DEM)
VVA ≤ 0.965 ft 95th Percentile (DEM)
Tested 0.061 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the Point Cloud was calculated using 29 independent checkpoints located in the Bare Earth and Urban land cover categories. The NVA of the Bare Earth was calculated using 67 independent checkpoints located in the Bare Earth and Urban land cover categories.
Tested 0.143 meters VVA was calculated using 53 checkpoints located in the Brushlands and Low Trees and Tall Weeds and Crops land cover categories at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for Lidar Data. Tested against the DEM.
Tested 0.060 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the DEM was calculated using 67 independent checkpoints located in the Bare Earth and Urban land cover categories.
Area of interest covers approximately 2,440 square miles around project area. The raw LAS data files included all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes NVA specifications. Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header.
All lidar data and lidar derived data covers the entire 2,440 square mile area of interest. All lidar point cloud tiles show no edge artifacts or mismatches from tile to tile. Void areas (i.e. areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header. Data cover the entire area specified for this project.
1
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
2017-10-27T00:00:00
2
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.
2017-11-25T00:00:00
3
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.
2019-07-02T00:00:00
4
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.
2019-07-02T00:00:00
5
Lidar Intensity Imagery Creation: All lidar intensity imagery was created from the final calibrated and classified lidar point cloud. Intensity images were produced from all classified points.
2019-07-02T00:00:00
6
Hydro line Collection: Hydro lines were compiled as water bodies (ponds and lakes) 2 acres or greater, and streams and rivers (“double-line”) 100 nominal feet wide or greater, using the lidar intensity data and surface terrain model of the entire project area. After the collection of hydro lines all features were validated for monotonicity and vertical variance, to ensure that no points were floating above ground. The hydro break lines were encoded into the lidar surface and used to hydro-enforce/flatten all significant water bodies. These final hydro lines were then used in the production of bare Earth digital models to hydro flatten significant water bodies.
2019-07-02T00:00:00
7
Bare-Earth Hydro-flattened DEMs were created in LP-360 from the hydro lines and bare-earth (ground) LiDAR data. All DEMs were created with a cell size of 6 feet. Delivery in an industry-standard, GIS-compatible, 32-bit ERDAS GeoTIFF raster format and cut to the project index tiles. Each surface is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface.
2019-07-19T00:00:00
8
The NOAA Office for Coastal Management (OCM) received 3052 raster DEM files in GeoTiff format from Tetra Tech. The data were in GA State Plane West, NAD83(2011), US Survey feet, coordinates and NAVD88 (Geoid12b) elevations in meters. The bare earth raster files were at a 6 ft grid spacing.
OCM performed the following processing on the data for Digital Coast storage and provisioning purposes:
1. Used internal script to assign the EPSG codes.
2. Copied to the files to https.
2019-08-22T00:00:00
Organization
Office for Coastal Management
OCM
2234 South Hobson Avenue
Charleston
SC
29405-2413
https://www.coast.noaa.gov/
57398
Data Set
2017 GA DNR Lidar: Middle Chattahoochee - Walter F Watershed
Cross Reference
gov.noaa.nmfs.inport:57266
Rebecca Mataosky
2019-08-22T16:06:05
SysAdmin InPortAdmin
2023-10-17T16:12:19
2019-09-11
OCM Partners
OCMP
1002
Public
No
2019-09-11
1 Year
2020-09-11