2011 Georgia Lidar DEM: Burke Richmond Lincoln Columbia Counties

TASK NAME:4 GA Counties of Elevation Data

NOAA Contract No. EA133C11CQ0010

Requisition No. NCNP0000-11-02615

Woolpert Order No. 71511

CONTRACTOR: Woolpert, Inc.

LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS positioning, and inertial measurement technologies. The LiDAR systems collect data point clouds that are used to produce highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures, and vegetation. The task required the LiDAR data to be collected at a nominal pulse spacing (NPS) of 1.0 meter. The final products include full classified LAS, hydrologically flattened four (4) foot pixel raster DEM's of the bare earth surface in ESRI Floating Point Grid Format (ArcGRID DEMs), and hydrologically flattened breaklines. Rasters were later convert to GeoTIFF format with vertical units of feet.

Original contact information:

Contact Org: National Oceanic and Atmospheric Administration (NOAA)

Title: Coastal Services Center

Phone: (843) 740-1200

This task order consisted of LiDAR data acquisition and processing for the National Oceanic and Atmospheric Administration's (NOAA) Coastal Services Center (CSC). The area of interest for this task order are four Counties in Georgia; Burke, Columbia, Lincoln and Richmond. The LiDAR data acquisition and processing for Burke, Lincoln and Richmond County was performed in the Winter of 2011. The LiDAR data acquisition and processing for Columbia County was performed under a separate contract in the Spring of 2011. The LiDAR data was provided to NOAA CSC, as part of the 4 GA Counties of Elevation Data task order. The 4 GA Counties of Elevation Data task order AOI encompasses approximately 1739 square miles. The area of interest acquired and processed for Columbia County is approximately 353 square miles. The task order requires the LiDAR data to be collected at a nominal pulse spacing (NPS) of 1.0 meter. The LiDAR data was collected to meet Fundamental Vertical Accuracy (FVA) Root Mean Square Error (RMSE) of 18.0 cm or better at a 95% confidence level, so that when combined with breaklines, the data adequately supports the generation of two (2) foot FEMA compliant contours. The final LiDAR data was delivered in 5,000' x 5,000' tiles using North American Datum 1983, Georgia State Plane Coordinate System, East Zone, and expressed in US Survey Feet.

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NOAA Contract No. EA133C11CQ0010

Requisition No. NCNP0000-11-02615

Woolpert Order No. 71511

CONTRACTOR: Woolpert, Inc.

The reflective surface data represents the DEM created by the laser energy reflected from the first surface encountered by the laser pulse. Some energy may continue beyond this initial surface, to be reflected by a subsequent surface as represented by the last return data. Intensity information is captured from the reflective surface pulse and indicates the relative energy returned to the sensor, as compared to the energy transmitted. The intensity image is not calibrated or normalized but indicates differences in energy absorption due to the interaction of the surface materials with laser energy, at the wavelength transmitted by the sensor. The bare earth model is created by identifying the returns that fall on the ground surface and by interpolating a surface between these points. In this manner, buildings and vegetation are removed from the bare earth model. This data set does not include bridges and overpasses in the bare earth model as the delineation point for these structures is not reliably discernible in the LiDAR data.

Any conclusions drawn from the analysis of this information are not the responsibility

of Woolpert, Georgia DNR, the NOAA Office for Coastal Management, or their partners.

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

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=5188

No restrictions apply to this data.

None. However, users should be aware that temporal changes may have occurred since this dataset was collected and that some parts of these data may no Longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of it's limitations. Acknowledgment of the Georgia Department of Natural Resources would be appreciated for products derived from these data. Acknowledgment of the NOAA Digital Coast for data distribution would also be appreciated.

None.

None.

The LiDAR collected for this task order was collected to meet a Fundamental Vertical Accuracy (FVA) of NSSDA RMSEZ = 18cm (NSSDA AccuracyZ 95% = 36cm) or better; assessment procedures to comply with FEMA guidelines. | Quantitative Value: 18 cm RMSE | Quantitative Test Explanation: Points measured will produce an error less than 18.0 cm RMSE.

Issues have been noted in the interpolation of lake surfaces. They are supposed to be hydroflattened, but there are lakes that have been extrapolated as either pits or domes.

Horizontal accuracy is +/- 4-foot (1.22 meters) at the 95% confidence level using RMSE(r) x 1.9600 as defined by the FGDC Geospatial Positional Accuracy Standards, Part 3: NSSDA. LiDAR system calibration is available in the project report.

The data collected under this Task Order meets the National Standard for Spatial Database Accuracy (NSSDA) accuracy standards. The NSSDA standards specify that vertical accuracy be reported at the 95 percent confidence level for data tested by an independent source of higher accuracy. (http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part3/index_html).

For Columbia County, the LiDAR data vertical accuracy RMSE is 6.1 cm (0.20 ft).

The Fundamental Vertical Accuracy (FVA) of the TIN: 11.96 cm (0.39 ft) at a 95% confidence level, derived according to NSSDA.

For Burke, Richmond, and Lincoln Counties, the LiDAR data vertical accuracy RMSE is 5.3 cm (0.175 ft).

The Fundamental Vertical Accuracy (FVA) of the TIN: 10.4 cm (0.34 ft) at a 95% confidence level, derived according to NSSDA.

Cloud Cover: 0

The LiDAR data is visually inspected for completeness to ensure that are no gaps between flight lines.

All formatted data are validated using commercial GIS software to ensure proper formatting and loading prior to delivery.