2003 NCFMP Lidar: NC Statewide Phase 2

Airborne LIDAR terrain mapping data acquired January through March 2003. Point data (XYZ) in ASCII format. Horizontal datum NAD83(1995) North Carolina State Plane feet. Vertical datum NAVD88 US Survey Feet. These data may represent a single geographic tile of a larger, county/sub-county data set. As such, the map extent indicated in the Spatial_Domain element is representative of the larger data set and not an individual tile. The data are organized in 10,000 ft x 10,000 ft tiles using the NC Bureau of Land Records Management (LRMP) standards. Specific information about individual data tiles is included in the data delivery index. LAS tiles were received at NOAA OCM.

These data were collected and derived by the North Carolina Floodplain Mapping Program as part of its effort to modernize FEMA Flood Insurance Rate Maps (FIRM) statewide. Although created for specific use in the engineering aspects of floodplain delineation, the data were also developed to address the elevation data requirements of the broader geospatial data user community. The North Carolina Floodplain Mapping Program was established in response to the extensive damage caused by Hurricane Floyd in 1999.

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A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/5010/supplemental/nc2003_ncfmp_phase2_m5010.kmz

Files in LAZ format (Unclassified, class 1 only)

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Any conclusions drawn from the analysis of this information are not the responsibility of NC Floodplain Mapping Program, EarthData, the NOAA Office for Coastal Management, or its partners.

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

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=5010;

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Users should be aware that temporal changes may have occurred since this data set was collected and that some parts of this data may no longer represent actual surface conditions.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.

These data sets were created with the highest consideration of accuracy and data integrity. However, as with all other geospatial data sets, users must take into consideration the consequences of using the data for specific applications, business processes, decisions, and map display. For example, surface conditions may have changed in some areas since the initial data was captured. A full metadata record is provided to help the user understand the date, map scale and accuracy standard applied in the collection and data development process. The data should not be used without full review and comprehension of the metadata. acknowledgement of the North Carolina Floodplain Mapping Program is appreciated when using the data set. Data further derived from this data set should be fully documented using the federal metadata standard and listed via the NC Geospatial Data Clearinghouse.

LIDAR full returns were compared with NCGS QA/QC checkpoints using only single and final returns per pulse. A vertical bias was aquired after airport calibration based on this comparison. For the NC Floodplain Mapping Program, the vertical accuracy for coastal counties is less than or equal to 20 cm

RMSE. For mainland counties, the vertical accuracy of the elevation data is less than or equal to 25 cm RMSE. | Quantitative Value: less than 20 cm | Quantitative Test Explanation: RMSE (cm) of bare earth LIDAR points compared with independent checkpoints

LIDAR full return mass points were compared with surveyed elevations provided by independent contractors to theNCGS.

More information about the Quality Control reports is available through NCFMP.

Numerous internal quality assurance/quality control steps taken to ensure the quality of the LIDAR terrain data to meet the bare earth requirements and RMSE accuracy standards in the NC Floodplain Mapping Program.

Step 1. Preprocessing

Step 2. Post-Automated Editing QC (Data Evaluation)

Step 3. QC Check of Tiles

Step 4. Manual Editing (Hillshade Checks / Peer Review)

Step 5. QC and Tile Edge Matching

Step 6. Final EarthData QC

Step 7. Comparisons of Independent Field Survey Data with LIDAR Data; Quantitative Value: 2 meters, Test that produced the value: RMSE (m) of bare earth LIDAR points compared with independent checkpoints

LIDAR full return mass points were compared with surveyed elevations provided by independent contractors to the NCGS. A vertical bias was acquired after airport calibration based on this comparison.

For the NC Floodplain Mapping Program, the vertical accuracy for coastal counties is less than or equal to 20 cm RMSE. For mainland counties, the vertical accuracy of the elevation data is less than or equal to 25 cm RMSE.

Numerous internal quality assurance/quality control steps were taken to ensure the quality of the LIDAR terrain data to meet the bare earth requirements and RMSE accuracy standards in the NC Floodplain Mapping Program.

Step 1. Preprocessing

Step 2. Post-Automated Editing QC (Data Evaluation)

Step 3. QC Check of Tiles

Step 4. Manual Editing (Hillshade Checks / Peer Review)

Step 5. QC and Tile Edge Matching

Step 6. Final EarthData QC

Step 7. Comparisons of Independent Field Survey Data with LIDAR Data; Quantitative Value: 0.20 meters, Test that produced the value: RMSE (m) of bare earth LIDAR points compared with independent checkpoints

The full return mass points contain voids where insufficient energy was reflected from the surface to generate a valid return from the terrain. Voids in the full return mass points tend to occur in water bodies. Wet sand and certain types of vegetation can also cause voids or anomalous elevations.

Data was vertically adjusted based on RMSE and mean difference from control report