2017 USGS Topobathy Lidar: Everglades National Park, FL

Product: These lidar data are processed Classified LAS 1.4 files, formatted to individual 1000 m x 1000 m tiles; used to create intensity images, 2D breaklines and Topobathy DEMs as necessary.

Geographic Extent: Florida Everglades National Park covering approximately 1,211 square miles.

Dataset Description: Florida Everglades National Park 2018 Lidar project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.35 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011), Universal Transverse Mercator, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to individual 1000 m x 1000 m tiles, as tiled Intensity Imagery, and as tiled bare earth topobathy DEMs; all tiled to the same 1000 m x 1000 m schema.

Ground Conditions: Lidar was collected in early to mid 2017, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Dewberry established a total of 47 ground control points that were used to calibrate the lidar to known ground locations established throughout the Florida Everglades National Park project area. An additional 120 independent accuracy checkpoints, 61 in Bare Earth and Urban landcovers (61 NVA points), 59 in Tall Grass and Brushland/Low Trees categories (59 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

This metadata record reflects the data that are available from the NOAA Digital Coast Data Access Viewer (DAV). The NOAA Office for Coastal Management (OCM) downloaded 3320 laz point data files from these USGS sites:

https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/FL_Everglades_NP_LiDAR_2017_D16/FL_Everglades_N_2017/LAZ/

https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/FL_Everglades_NP_LiDAR_2017_D16/FL_Everglades_S_2017/LAZ/

The data were processed to the NOAA Digital Coast Data Access Viewer (DAV) to make the data available for bulk and custom downloads.

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Intensity Images, Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D Topobathy Digital Elevation Model (DEM) with a 0.5 meter cell size. These lidar point cloud data were used to create intensity images, 2D breaklines, and Topobathy DEMs as necessary.

USGS Contract No. G16PC00020 CONTRACTOR: Dewberry Lidar data were acquired and calibrated by Dewberry, and all follow-on processing was completed by Dewberry.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey (USGS) - National Geospatial Program (NGP) Lidar Base Specification v1.2",

"ldrsens" : "Riegl LMS-Q680i",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.35",

"ldrdens" : "8",

"ldranps" : "0.35",

"ldradens" : "8",

"ldrfltht" : "400",

"ldrfltsp" : "130",

"ldrscana" : "60",

"ldrscanr" : "191",

"ldrpulsr" : "400",

"ldrpulsd" : "3",

"ldrpulsw" : "0.9",

"ldrwavel" : "1550",

"ldrmpia" : "1",

"ldrbmdiv" : "1",

"ldrswatw" : "462",

"ldrswato" : "30",

"ldrgeoid" : "National Geodetic Survey (NGS) GEOID12B"

},

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey (USGS) - National Geospatial Program (NGP) Lidar Base Specification v1.2",

"ldrsens" : "Riegl VQ-820G",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.35",

"ldrdens" : "8",

"ldranps" : "0.35",

"ldradens" : "8",

"ldrfltht" : "400",

"ldrfltsp" : "130",

"ldrscana" : "60",

"ldrscanr" : "200",

"ldrpulsr" : "522",

"ldrpulsd" : "1.2",

"ldrpulsw" : "0.36",

"ldrwavel" : "532",

"ldrmpia" : "1",

"ldrbmdiv" : "1",

"ldrswatw" : "307",

"ldrswato" : "30",

"ldrgeoid" : "National Geodetic Survey (NGS) GEOID12B"

},

"ldraccur" : {

"ldrchacc" : "0.227",

"rawnva" : "0.085",

"rawnvan" : "60",

"clsnva" : "0.070",

"clsnvan" : "61",

"clsvva" : "0.350",

"clsvvan" : "59"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

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

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

"lasintrz" : "16",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare Earth Ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

},

"lasclass" : {

"clascode" : "40",

"clasitem" : "Submerged Topography/Bathymetry"

},

"lasclass" : {

"clascode" : "41",

"clasitem" : "Water Surface"

},

"lasclass" : {

"clascode" : "45",

"clasitem" : "Water Column/No Bottom Found"

}

}}

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.

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.

The project specifications require that only Non-Vegetated Vertical Accuracy (NVA) be computed for raw lidar point cloud swath files. The required accuracy (ACCz) is: 19.6 cm at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 10 cm in the "bare earth" and "urban" land cover classes.

Dewberry Determined Vertical Accuracy

The NVA was tested with 60 checkpoints located in bare earth and urban (non-vegetated) areas. These check points were not used in the calibration or post processing of the lidar point cloud data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. Elevations from the unclassified lidar surface were measured for the x,y location of each check point. Elevations interpolated from the lidar surface were then compared to the elevation values of the surveyed control points. AccuracyZ has been tested to meet 19.6 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines. Tested 0.085 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the raw lidar point cloud swath files was calculated against TINs derived from the final calibrated and controlled swath data using 60 independent checkpoints located in Bare Earth and Urban land cover classes.

USGS Determined Vertical Accuracy

Non-Vegetated Vertical Accuracy (NVA) = 7.29 cm at the 95% Confidence Level or 3.7 cm RMSE

Vegetated Vertical Accuracy (VVA) = 33.51 cm at the 95th Percentile

Bathymetric Vertical Accuracy = 38.73 cm at the 95% Confidence Level

Refer to the USGS project report in the URL section of this metadata record.

These LAS data files include 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 Non-Vegetated Vertical Accuracy specifications.

Data covers the entire area specified for this project.

Data is backed up to tape and to cloud storage.

Data were collected and processed by Dewberry and were made available on the USGS rockyweb site. The data were downloaded from the USGS rockyweb site by the NOAA Office for Coastal Management (OCM) where the data were processed to make it available for custom download from the NOAA Digital Coast Data Access Viewer (DAV) and bulk download from AWS S3.