2019 NOAA NGS Topobathy Lidar DEM: Finger Lakes, NY

NOAA Finger Lakes Topobathymetric lidar project data were collected by National Oceanic and Atmospheric Administration (NOAA) using a Riegl VQ-880-G sensor system. The NOAA Finger Lakes Topobathymetric project lidar acquisition was flown between 20190913 and 20191109 in 23 missions. The NOAA Finger Lakes topobathymetric lidar project dataset includes topobathymetric data in a LAS format 1.4, point data record format 6, with the following classifications in accordance with project specifications and the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards:

1 - unclassified

2 - ground

7 Withheld -low noise

18 Withheld - high noise

40 - bathymetric bottom or submerged topography

41 - water surface

43 - submerged feature

45 - water column

64 - Submerged Aquatic Vegetation (SAV)

65 - overlap bathymetric bottom - temporally different from a separate lift

1 Withheld - edge clip

This dataset also includes lidar intensity values, number of returns, return number, time, and scan angle. The full NOAA Finger Lakes Topobathymetric Lidar project boundary extent covers 301,150 acres (~1,219 sqKm). LAS files were compiled in 500 m x 500 m tiles. The final classified lidar data were then transformed from ellipsoid (GRS80) to geoidal height (Geoid18) and used to create topobathymetric DEMs in GeoTIFF format with 1m pixel resolution. This project dataset represents an area covering 141 - 5000 m x 5000 m boundary-clipped 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 Finger Lakes topobathymetric lidar 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), 40 (submerged topography), and 43 (submerged object), were used to create the final DEMs. The full workflow used for this project is documented in the NOAA Finger Lakes Topobathymetric Lidar final report and is available upon request.

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners

Data is available online for bulk or 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.

OS Independent

Lidar horizontal accuracy is a function of Global Navigation Satellite System (GNSS) derived positional error, flying altitude, and INS derived attitude error. The obtained RMSEr value is multiplied by a conversion factor of 1.7308 to yield the horizontal component of the National Standards for Spatial Data Accuracy (NSSDA) reporting standard where a theoretical point will fall within the obtained radius 95 percent of the time (ACCr). For the Finger Lakes project, the horizontal accuracy was determined using the IMU/GNSS performance measurements reported by Riegl for the VQ-880-G lidar sensor. Based on a flying altitude of 396 meters, an IMU error of 0.0025 decimal degrees, and a GNSS positional error of 0.05 meters, this project met 0.06 m horizontal accuracy at the 95% confidence level.

Absolute accuracy was assessed using Non-Vegetated Vertical Accuracy (NVA) survey methods, utilizing survey check points evenly distributed as feasible throughout the project area. 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 ground classified lidar point cloud. 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 Finger Lakes project area, 400 survey checkpoints were used to assess the non-vegetated vertical accuracy against the derived bare earth DEM. Project specifications require NVA meet 0.196 m accuracy at the 95% confidence interval. The final NOAA Finger Lakes Topobathymetric Lidar project technical report details final project vertical accuracies.

The project dataset Non-Vegetated Vertical Accuracy tested 0.093 m vertical accuracy at 95% confidence level against the derived bare earth DEM in open terrain using 400 ground check points, based on RMSEz (0.047 m) x 1.9600.

Data covers the project boundary.

Not applicable

Data is backed up to tape and to cloud storage.