2018 NOAA NGS Topobathy: Key Largo, Florida

These data were collected by the National Oceanic Atmospheric Administration National Geodetic Survey Remote Sensing Division using a Riegl VQ880G system. The data includes topobathy data in an LAS 1.2 format file and may contain the following classifications: unclassified (1), ground (2), noise (7), bathymetric point (40), topobathy water surface (41), submerged object (43), and Submerged Aquatic Vegetation (64) in accordance with the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards. This data set may also include lidar intensity values and encoded RGB image values.

This lidar data are an ancillary product of NOAA's Coastal Mapping Program (CMP), created through a wider Integrated Ocean and Coastal Mapping initiative to increase support for multiple uses of the data. It is not intended for mapping, charting, or navigation. In addition, it will be used for ongoing research efforts for testing and developing standards for airborne lidar.

Data include all lidar returns. Outliers or false returns (e.g., returns from birds, atmospheric particles, and/or system noise) may be present in the data. An automated ground classification algorithm was used to determine bare earth point classification. It should be noted that not all returns were correctly classified; therefore the user should examine for acceptability.

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.

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be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions.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

Horizontal Positional Accuracy was not assessed.

NOAA utilized 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°) where the LiDAR system has a high probability of measuring the ground surface and is evaluated at the 95% confidence interval (1.96*RMSE). Project specifications require NVA meet 0.196 m accuracy at the 95% confidence interval.

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 dataset tested 0.106 m vertical accuracy at 95% confidence level in open terrain.

Not applicable

Data is backed up to tape and to cloud storage.