2011 USGS Topographic LiDAR: Suwannee River Expansion

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This graphic shows the lidar coverage for portions of Hamilton, Lafayette, Madison, Suwannee, Columbia, Union, Bradford, Gilchrist, Dixie, and Levy Counties in Florida.

Date that the source FGDC record was last modified.

Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using 'fgdc_to_inport_xml.pl' script. Contact Tyler Christensen (NOS) for details.

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Partial upload to move data access links to Distribution Info.

The ABGPS, inertial measurement unit (IMU), and raw scans are collected during the LiDAR aerial survey. The ABGPS monitors the xyz position of the sensor and the IMU monitors the orientation. During the

aerial survey, laser pulses reflected from features on the ground surface are detected by the receiver optics and collected by the data logger. GPS locations are based on data collected by receivers on the

aircraft and base stations on the ground. The ground base stations are placed no more than 40 km radius from the flight survey area.

The ABGPS, IMU, and raw scans are integrated using proprietary software developed by Leica and delivered with the Leica System. The resultant file is in a LAS binary file format. The LAS version 1.2 file format

can be easily transferred from one file format to another. It is a binary file format that maintains information specific to the LiDAR data (return number, intensity value, xyz, etc.). The resultant points are

produced in the NAD83/2007 HARN State Plane Florida North Coordinate System, with units in U.S. Feet and referenced to the NAVD88 datum. The LiDAR mass points were processed in American Society for Photogrammetry

and Remote Sensing LAS 1.2 format. The header file for each dataset is complete as defined by the LAS 1.2 specification. The datasets were divided into a 5000 ft by 5000 ft tiling scheme, based on the Florida state

grid network. The tiles are contiguous, do not overlap, and are suitable for seamless topographic data mosaics that include no "no data" areas. The names of the tiles include numeric column and row designations and

all files utilize the LAS file extension

The unedited data are classified to facilitate the application of the appropriate feature extraction filters. A combination of proprietary filters are applied as appropriate for the production of bare earth

digital elevation models (DEMs). Interactive editing methods are applied to those areas where it is inappropriate or impossible to use the feature extraction filters, based upon the design criteria and/or

limitations of the relevant filters. These same feature extraction filters are used to produce elevation height surfaces.

Filtered and edited data are subjected to rigorous QA/QC, according to the 3001 Operating Unit Quality Control Plan and procedures. A series of quantitative and visual procedures are employed to validate the accuracy

and consistency of the filtered and edited data. Ground control is established by Northrop Grumman, 3001 Operating Unit and GPS-derived ground control points (GCPs) in various areas of dominant and prescribed land cover.

These points are coded according to land cover, surface material, and ground control suitability. A suitable number of points are selected for calculation of a statistically significant accuracy assessment, as per the

requirements of the National Standard for Spatial Data Accuracy. A spatial proximity analysis is used to select edited LiDAR data points within a specified distance of the relevant GCPs. A search radius decision rule is

applied with consideration of terrain complexity, cumulative error, and adequate sample size. Accuracy validation and evaluation is accomplished using proprietary software to apply relevant statistical routines for

calculation of Root Mean Square Error (RMSE) and the National Standard for Spatial Data Accuracy (NSSDA), according to Federal Geographic Data Committee (FGDC) specifications.

The NOAA Office for Coastal Management (OCM) received topographic files in LAS 1.2 format. The files contained lidar

elevation measurements. The data were received in Florida State Plane North Zone 0903, NAD83 coordinates

and were vertically referenced to NAVD88 using the Geoid09 model. The vertical units of the data were

feet. OCM performed the following processing for data storage and Digital Coast provisioning purposes:

1. The topographic las files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid09.

2. The topographic las files were converted from a Projected Coordinate System (FL SP North) to a Geographic Coordinate system (NAD83).

3. The topographic las files' vertical units were converted from feet to meters.

4. The topographic las files' horizontal units were converted from feet to decimal degrees.

5. Class 11 (Witheld) was changed to Class 13.