2015 SRWMD Lidar DEM: North Central Florida

This data set extends to a 100 meter buffer around SRWMD LiDAR Gaps in North Central FL BAA-FY15 boundary, which covers parts of Baker, Columbia, Dixie, Gilchrist, Hamilton, Jefferson, Lafayette, Levy, Madison, Taylor, and Union Counties in Florida, approximately 2030 Square Miles. This data set was created from LiDAR point cloud LAS swath files and tiled Las files. Each LAS file contains LiDAR point information, which has been calibrated, controlled, and classified.

Ground Conditions: water at normal levels; no unusual inundation; no snow; leaf off USGS-NGP Base Lidar Specification v1.2

The NOAA Office for Coastal Management (OCM) received the DEM tif files from the Suwannee River Water Management District (SRWMD) and processed the data to the Data Access Viewer (DAV) and to https. The total number of files processed was 2945.

In addition to these bare earth Digital Elevation Model (DEM) data, the lidar point data that these DEM data were created from, and the hydro breaklines are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

The USGS/NGTOC contracted Digital Aerial Solutions, LLC to obtain professional services related to the planning,acquisition and development of Light Detection and Ranging (Lidar) data and derivative products. The task order is for a QL2 Lidar survey to be collected over Baker, Columbia, Dixie, Gilchrist, Hamilton, Jefferson, Lafayette, Levy, Madison, Taylor, and Union Counties in Florida. The deliverable products would be used by the USGS/NGTOC for conservation planning, design, research, floodplain mapping, wetlands identification, dam safety assessments, hydrologic modeling, and other environmental purposes.

All Lidar data and associated products were acquired, calibrated, and used in the creation of Lidar derived products by Digital Aerial Solutions, LLC.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Lidar Specification v1.2

",

"ldrsens" : "Leica ALS80-HP

",

"ldrmaxnr" : "Unlimited

",

"ldrnps" : "0.7

",

"ldrdens" : "4.0

",

"ldranps" : "0.71

",

"ldradens" : "2.0

",

"ldrfltht" : "1600

",

"ldrfltsp" : "120

",

"ldrscana" : "40

",

"ldrscanr" : "44.9

",

"ldrpulsr" : "335.2

",

"ldrpulsd" : "4

",

"ldrpulsw" : "0.46

",

"ldrwavel" : "1064

",

"ldrmpia" : "1

",

"ldrbmdiv" : "0.15

",

"ldrswatw" : "1165

",

"ldrswato" : "20

",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid 12B

"

},

"ldraccur" : {

"ldrchacc" : "0.643

",

"rawnva" : "0.432

",

"rawnvan" : "95

",

"clsnva" : "0.429

",

"clsnvan" : "95

",

"clsvva" : "0.941

",

"clsvvan" : "74

"

},

"lasinfo" : {

"lasver" : "1.4

",

"lasprf" : "6

",

"laswheld" : "Withheld (ignore) points were identified in the files using the standard LAS Withheld bit.

",

"lasolap" : "Swath overage points were identified in these files using the standard LAS overlap bit.

",

"lasintr" : "16

",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Undetermined/Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare earth"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridges"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

LiDAR Tiles and associated derived products for SRWMD LiDAR Gaps in North Central FL BAA-FY15

The data represented is the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of data collection. As such, it is only valid for its intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than its intended purpose.

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 and custom downloads.

No restrictions apply to this data the data represented is the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of the data collection. As such, it is only valid for its intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than its intended purpose.

None, however, users should be aware that temporal changes may have occurred since this data set was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of the limitations of the data. Acknowledgment of the US Geological Survey would be appreciated for products derived from these data. The data represented is the result of data collection and processing per contract specifications and indicates the general existing conditions at the time of the data collection. As such, it is only valid for its intended use, content, time, and accuracy specifications. The user is responsible for the results of any application of the data for other than its intended purpose.

Inertial Explorer ver: 8.6; Leica CloudPro Ver:1.2.1; GeoCue Ver: 2014.1.21.4; Microstation V8i; Terresolid ver: 2015; LP360 ver: 2014.1.51.1; Arcmap ver: 10.4; Global Mapper ver: 16

Horizontal error in lidar derived elevation data is largely a function of positional error as derived from the Global Navigation Satellite System (GNSS), attitude (angular orientation) error (as derived from the INS) and flying altitude; and can be estimated based on these parameters. As described in Section 7.5 of the ASPRS Positional Accuracy Standards for Digital Geospatial Data the horizontal errors in lidar data are largely a function of GNSS positional error, INS angular error, and flying altitude. Therefore lidar data collected with GNSS error of 0.05m and the IMU error of 0.03492 degrees at an altitude of 10,500 feet MSL; the expected radial horizontal positional error will be RMSEr = 0.367 US Survey Ft (11.2 cm).

Vertical Accuracy of the bare-earth lidar data was assessed and reported in accordance with the ASPRS Positional Accuracy Standards for Digital Geospatial Data; One hundred and sixty-nine (169) surveyed points were measured for the purpose of assessing the accuracy of the SRWMD LiDAR Gaps in North Central FL BAA-FY15 (95 NVA + 74 VVA). Both data sets, Lidar and Digital Elevation Models (DEMs) have been tested for their individual vertical accuracy levels. The Lidar was tested by using interpolation while the DEMs where tested by extracting the elevation of a pixel containing the checkpoint. All DEM Vertical accuracy results are reported in the DEM Metadata reports while this project wide Metadata file is reporting the vertical accuracy results from the the source Lidar. Required Vegetated Vertical Accuracy (VVA): 0.965 US Survey Ft. Required Non Vegetated Vertical Accuracy (NVA) : 0.643 US Survey Ft. This data set was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 0.328 US Survey Ft RMSEz Vertical Accuracy Class. Actual NVA accuracy was found to be RMSEz = 0.219 US Survey Ft (6.8 cm) equating to +/-0.429 US Survey Ft (13.1 cm ) at 95% confidence level.

Calculated Non-Vegetated Vertical Accuracy (NVA) of the Digital Elevation Model: 0.435 US Survey Ft (13.3 cm)

RMSE is 6.8 cm

Number of Check Points used to calculate the Reported (NVA) for the Digital Elevation Model: 95

Calculated (VVA) of the Digital Elevation Model: 0.932 US Survey Ft (28.4 cm)

Number of Check Points used to calculate the Reported (VVA) for the Digital Elevation Model: 74

The raw LAS data files included all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes Fundamental Vertical Accuracy specifications.Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header.

Aerial LiDAR data covers the entire area of Interest intended for this project task. All LiDAR Point Cloud tiles show no edge artifacts or mismatches from tile to tile. Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header. Data cover the entire area specified for this project.

Data is backed up to tape and to cloud storage.