2017 NOAA NGS Topobathy Lidar DEM (with voids): Fort Lauderdale to Miami (FL)

These data were collected by the National Oceanic and Atmospheric Administration (NOAA), National Geodetic Survey (NGS), Remote Sensing Devision (RSD), Coastal Mapping Program (CMP) using a Riegl VQ880G system. Quantum Spatial Inc (QSI) was contracted by NOAA to process the topobathymetic LiDAR data. The NOAA Miami Florida Intracoastal Topobathy (Miami Intracoastal) data were acquired from 20170224 - 20170310 in five missions. The Miami Intracoastal dataset includes topobathy data in a LAS 1.2 format file with the following classification: unclassified (1), ground (2), noise (7), overlap default (19), overlap ground (20), overlap water column (21), water column (25), bathymetric bottom or submerged topography (26), submerged feature (29), and temporal bathy bottom (31) in accordance with project specifications. The contracted project consists of approximately 53,381 acres along the Atlantic Coast of Miami, Florida. This dataset delivery represents the full NOAA Miami Florida Intracoastal Topobathy LiDAR Processing area. LAS files were compiled by 500 m x 500 m tiles. The final classified LiDAR data were then used to create topobathymetric DEMs in IMG format with 1m pixel resolution. This Miami Intracoastal dataset represents an area covering 15 - 5000 m x 5000 m DEM tiles.

This lidar data was required by National Oceanic and Atmospheric Administration (NOAA), the National Geodetic Survey (NGS), Remote Sensing Division Coastal Mapping Program (CMP) to enable accurate and consistent measurement of the national shoreline. The CMP works to provide a regularly updated and consistent national shoreline to define America's marine territorial limits and manage coastal resources.

The Miami Intracoastal data includes all lidar returns. An automated grounding classification algorithm was used to determine bare earth and submerged topography point classification. The automated grounding was followed with manual editing. Classes 2 (ground) and 26 (submerged topography) were used to create the final DEMs. The full workflow used for this project is documented in the NOAA Miami Florida Intracoastal Topobathymetric LiDAR Processing final report.

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the National Geodetic Survey, the 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=6271;

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.

OS Independent

NOAA provided QSI 2 sets of ground survey points in order to evaluate accuracy. Absolute accuracy was assessed using Non-Vegetated Vertical Accuracy (NVA) survey methods. NVA compares known ground check point data that were withheld from the calibration and post-processing of the LiDAR point cloud to the triangulated surface generated by the LiDAR points that were calibrated and post-processed. NVA is a measure of the accuracy of LiDAR point data in open areas with level slope (less than 20 degrees) where the LiDAR system has a high probability of measuring the ground surface and is evaluated at the 95% confidence interval (1.96*RMSE). In the NOAA Miami Florida Intracoastal Topobathy LiDAR Processing area, one file provided (FL1703_ICW01_gcp_tscan) contained 136 survey checkpoints that were used to assess the non-vegetated vertical accuracy. An additional file (FL1703_ICW01_pro_tscan) contained 704 survey checkpoints that were also used to assess vertical accuracy. Project specifications require NVA meet 0.196 m accuracy at the 95% confidence interval.

Not tested

Using NSSDA and FEMA methodology, the non-vegetated vertical accuracy (NVA) at the 95% confidence level (called Accuracyz) was computed by the formula RMSEz x 1.9600. The South Carolina Miami Intracoastal dataset tested 0.097 m vertical accuracy at 95% confidence level in open terrain using 136 ground check points provided in the FL1703_ICW01_gcp_tscan.txt file provided by NOAA, based on RMSEz (0.050 m) x 1.9600.

Using NSSDA and FEMA methodology, the non-vegetated vertical accuracy (NVA) at the 95% confidence level (called Accuracyz) was computed by the formula RMSEz x 1.9600. The South Carolina Miami Intracoastal dataset tested 0.095 m vertical accuracy at 95% confidence level in open terrain using 704 ground check points provided in the FL1703_ICW01_pro_tscan.txt file provided by NOAA, based on RMSEz (0.049 m) x 1.9600.