2019 USACE NCMP Topobathy Lidar: East Coast (NC)

These files contain classified topo/bathy lidar data. Data are classified as 1 (valid non-ground topographic data), 2 (valid ground topographic data), and 29 (valid bathymetric data). Classes 1 and 2 are defined in accordance with the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards. These data were collected by the Coastal Zone Mapping and Imaging Lidar (CZMIL) system. CZMIL integrates a lidar sensor with simultaneous topographic and bathymetric capabilities, a digital camera and a hyperspectral imager on a single remote sensing platform for use in coastal mapping and charting activities. Native lidar data is not generally in a format accessible to most Geographic Information Systems (GIS). Specialized in-house and commercial software packages are used to process the native lidar data into 3-dimensional positions that can be imported into GIS software for visualization and further analysis.

Planned data coverage for this dataset included a 1500-meter swath of the North Carolina shoreline , Dare County, North Carolina and parts of the North Carolina Keys. Topographic lidar coverage was obtained from the shoreline onshore 500 meters. Bathymetric lidar coverage extends from the shoreline offshore 1000 meters or to laser exinction, whichever occurs first. planned point spacing is 70 centimeters on land and in shallow water. In deeper water the planned point spacing decreases to 2 meters. Gaps or data holidays may exist in the data coverage. They arise due to a number of operational and environmental conditions, including but not limited to, airspace restrictions, high terrain, active surf, low-reflectivity bottom substrate materials and turbidity in the water column.

In addition to the lidar point data, topobathy bare earth Digital Elevation Models (DEMs) at a 1 meter grid spacing, created from the lidar point data, and the RGB imagery are also available from the NOAA Digital Coast. Links to these data are provided in the URL section of this metadata record.

DEMs that were created from all classes of points (1, 2, 29) at a 1 meter grid size are available by request via email at: coastal.info@noaa.gov. These products have not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA or OCM.

Original contact information:

Contact Org: JALBTCX

Title: Data Production Manager

Phone: 228-252-1131

Email: JALBTCX@usace.army.mil

This data was collected by USACE on behalf of the USACE NCMP to assess elevations above and below water along the coast of Connecticut and North Carolina.

These data have been developed from the best available sources. Although efforts have been made to ensure that the data are accurate and reliable, errors and variable conditions originating from physical sources used to develop the data may be reflected in the data supplied. Users must be aware of these conditions and bear responsibility for the appropriate use of the information with respect to possible errors, scale, resolution, rectification, positional accuracy, development methodology, time period, environmental and climatic conditions and other circumstances specific to these data. The user is responsible for understanding the accuracy limitations of the data provided herein. The burden for determining fitness for use lies entirely with the user. The user should refer to the accompanying metadata notes for a description of the data and data development procedures. Any conclusions drawn from the analysis of this information are not the responsibility of USACE, JALBTCX, the Office for Coastal Management, or its partners

Data is available online for bulk or custom downloads

These data have been developed from the best available sources. Although efforts have been made to ensure that the data are accurate and reliable, errors and variable conditions originating from physical sources used to develop the data may be reflected in the data supplied. Users must be aware of these conditions and bear responsibility for the appropriate use of the information with respect to possible errors, scale, resolution, rectification, positional accuracy, development methodology, time period, environmental and climatic conditions and other circumstances specific to these data. The user is responsible for understanding the accuracy limitations of the data provided herein. The burden for determining fitness for use lies entirely with the user. The user should refer to the accompanying metadata notes for a description of the data and data development procedures.

These data depict the heights at the time of the survey and are only accurate for that time. Acknowledgement of the Joint Airborne Lidar Bathymetry Technical Center of eXpertise (JALBTCX) would be appreciated in any publications or derived products. The data herein, including but not limited to geographic data, tabular data, analytical data, electronic data structures or files, are provided "as is" without warranty of any kind, either expressed or implied, or statutory, including, but not limited to, the implied warranties or merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the data is assumed by the user. No guarantee of accuracy is granted, nor is any responsibility for reliance thereon assumed. In no event shall the U.S. Army Corps of Engineers, Mobile District Office, Spatial Data Branch be liable for direct, indirect, incidental, consequential or special damages of any kind, including, but not limited to, loss of anticipated profits or benefits arising out of use of or reliance on the data. The Spatial Data Branch does not accept liability for any damages or misrepresentation caused by inaccuracies in the data or as a result of changes to the data caused by system transfers or other transformations or conversions, nor is there responsibility assumed to maintain the data in any manner or form. 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 its limitations.

Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.5.0.6491

CZMIL topographic data - Compiled to meet 1 m horizontal accuracy at 95% confidence level. CZMIL bathymetric data - Compiled to meet 3.5 + 0.05d m horizontal accuracy at 95% confidence level, d is depth.

JALBTCX evaluates the horizonal accuracy of the final data coverage against availlable basemap imagery products. The final lidar point cloud is gridded according to proceedures defined in the JALBTCX Standard Operating Guide and Appendices (SOGA). The grid products are then visually compared to basemap imagery products to verify the horizontal positions of large buildings and other urban features with the data coverage

CZMIL topographic data - Compiled to meet 20 cm vertical accuracy at 95% confidence level. CZMIL bathymetric shallow FOV data - Compiled to meet SQRT((0.20^2) +((0.0075d)^2)) m vertical accuracy at 95% confidence level, d is depth. CZMIL bathymetric deep FOV data - Compiled to meet SQRT((0.30^2) +((0.013d)^2)) m vertical accuracy at 95% confidence level, d is depth.

JALBTCX evaluates the vertical accuracy of the final data coverage against traditional ground-truth data. Ground-truth data is acquired and utilized according to specifications outlined in the JALBTCX Standard Operating Guide and Appendices (SOGA) as well as the USGS Lidar BaseSpecification. The final lidar point cloud at every project ground-truth location is compared against ground-truth points in the 'bare_ground' class. Comparisons are performed in the QCoherent LP360 software package, and the final results are output to JALBTCX's Ground Truth Comparison Report.

Every effort within operational constraints was made to achieve the intended data coverage and planned point densities.

JALBTCX evaluates final data coverage using techniques that are common to the lidar industry. These techniques are performed in a 3D environment for visual review of the final data coverage and verification of data alongside lidar waveforms and imagery collected concurrent with the lidar. Data reviewers perform checks to verify (1) extreme high and/or low elevation values have been invalidated, (2) elevations in areas of swath overlap are internally consistent, (3) binned standard deviation values meet CZMIL specifications, (4) point cloud classifications are valid, and (4) CZMIL processing modes are valid.

Data is backed up to tape and to cloud storage.

These data were collected using the CZMIL system. It is owned and operated by the U.S. Army Corps of Engineers (USACE). The system collects topobathy lidar data at 10 kHz and RGB imagery at 2 Hz. A CASI-1500 hyperspectral line scanner is integrated with the system as well. Aircraft position, velocity and acceleration information are collected through a combination of Novatel and POS A/V 510 equipment.