2018 USGS Lidar: South Texas

Product: This lidar data set includes unclassified swath LAS 1.4 files, classified LAS 1.4 files, breaklines, digital elevation models (DEMs), and intensity imagery.

Geographic Extent: The South Texas 2018 LiDAR AOI includes 30 counties in Texas, covering approximately 22,229 total square miles.

Dataset Description: The South Texas 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 0.7 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LiDAR Specification, Version 1.2. The data were developed based on a horizontal projection/datum of NAD 1983 (2011), UTM Zone 14, meters and vertical datum of NAVD88 (GEOID12B), meters. LiDAR data were delivered as processed Classified LAS 1.4 files formatted to 26,260 individual 1,500-meter x 1,500-meter tiles, as tiled intensity imagery, and as tiled bare earth DEMs; all tiled to the same 1,500-meter x 1,500-meter schema. Continuous breaklines were produced in Esri file geodatabase format. Ground Conditions: LiDAR was collected in winter and spring 2018 and winter 2019, 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, Quantum Spatial, Inc. utilized a total of 492 ground control points that were used to calibrate the LiDAR to known ground locations established throughout the project area. An additional 662 independent accuracy checkpoints, 390 in Bare Earth and Urban landcovers (390 NVA points), 272 in Tall Weeds categories (272 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

The NOAA Office for Coastal Management (OCM) downloaded this data set in 8 blocks from this USGS site:

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/

The blocks downloaded were:

USGS_LPC_TX_South_B1_2018_LAS_2019/ Number of files: 2560

USGS_LPC_TX_South_B2_2018_LAS_2019/ Number of files: 2438

USGS_LPC_TX_South_B3_2018_LAS_2019/ Number of files: 3886

USGS_LPC_TX_South_B4_2018_LAS_2019/ Number of files: 3788

USGS_LPC_TX_South_B5_2018_LAS_2019/ Number of files: 3941

USGS_LPC_TX_South_B6_2018_LAS_2019/ Number of files: 3998

USGS_LPC_TX_South_B7_2018_LAS_2019/ Number of files: 2650

USGS_LPC_TX_South_B8_2018_LAS_2019/ Number of files: 2943

These files were processed to the Data Access Viewer (DAV) and https. The total number of files downloaded and processed was 26,204.

Hydro breaklines are also available. These data are available for download at the link provided in the URL section of this metadata record. Please note that these products have not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA or OCM.

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 DEMs. The purpose of these LiDAR data was to produce high accuracy 3D hydro-flattened digital elevation models (DEMs) with a 1-meter cell size. These raw LiDAR point cloud data were used to create classified LiDAR LAS files, intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

USGS Contract No. G16PC00016, Task Order No. 140G0218F0075; CONTRACTOR:

Quantum Spatial, Inc.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

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

"ldrsens" : "Riegl VQ1560i",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.7",

"ldrdens" : "2.0",

"ldranps" : "0.63",

"ldradens" : "2.52",

"ldrfltht" : "2000",

"ldrfltsp" : "160",

"ldrscana" : "29",

"ldrscanr" : "174",

"ldrpulsr" : "700",

"ldrpulsd" : "3",

"ldrpulsw" : "0.36",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.18",

"ldrswatw" : "2217.0",

"ldrswato" : "20",

"ldrgeoid" : "GEOID 12B",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 14, meters"

},

"ldrinfo" : {

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

"ldrsens" : "Riegl LMS Q1560",

"ldrmaxnr" : "unlimited",

"ldrnps" : "0.7",

"ldrdens" : "2.0",

"ldranps" : "0.63",

"ldradens" : "2.52",

"ldrfltht" : "2200",

"ldrfltsp" : "160",

"ldrscana" : "30",

"ldrscanr" : "178",

"ldrpulsr" : "533",

"ldrpulsd" : "3",

"ldrpulsw" : "0.55",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.25",

"ldrswatw" : "2540.0",

"ldrswato" : "30",

"ldrgeoid" : "GEOID 12B",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 14, meters"

},

"ldrinfo" : {

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

"ldrsens" : "Orion H300",

"ldrmaxnr" : "4",

"ldrnps" : "0.7",

"ldrdens" : "2.0",

"ldranps" : "0.64",

"ldradens" : "2.44",

"ldrfltht" : "1700",

"ldrfltsp" : "153",

"ldrscana" : "18",

"ldrscanr" : "53",

"ldrpulsr" : "225",

"ldrpulsd" : "4",

"ldrpulsw" : "0.42",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.25",

"ldrswatw" : "1105.0",

"ldrswato" : "30",

"ldrgeoid" : "GEOID 12B",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 14, meters"

},

"ldrinfo" : {

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

"ldrsens" : "Leica ALS70",

"ldrmaxnr" : "4",

"ldrnps" : "0.7",

"ldrdens" : "2.0",

"ldranps" : "0.6",

"ldradens" : "2.78",

"ldrfltht" : "1950",

"ldrfltsp" : "155",

"ldrscana" : "18",

"ldrscanr" : "56",

"ldrpulsr" : "285",

"ldrpulsd" : "4",

"ldrpulsw" : "0.43",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1267.0",

"ldrswato" : "16",

"ldrgeoid" : "GEOID 12B",

"ldrcrs" : "NAD 1983 2011 UTM Zone 14N, Meter"

},

"ldrinfo" : {

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

"ldrsens" : "Leica ALS80",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.7",

"ldrdens" : "2.0",

"ldranps" : "0.57",

"ldradens" : "3.08",

"ldrfltht" : "2294",

"ldrfltsp" : "143",

"ldrscana" : "17",

"ldrscanr" : "47",

"ldrpulsr" : "303",

"ldrpulsd" : "2.5",

"ldrpulsw" : "0.5",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1403.0",

"ldrswato" : "12",

"ldrgeoid" : "GEOID12B",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 14, meters"

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0.090",

"rawnvan" : "390"

},

"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",

"lasintr" : "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" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

Any conclusions drawn from the analysis of this information are not the responsibility of Quantum Spatial, Inc, USGS, 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. The NVA was tested with 390 checkpoints located in bare earth and urban (non-vegetated) areas. These checkpoints 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 checkpoint. 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.

The project specifications require the accuracy (ACCz) of the derived DEM be calculated and reported in two ways:

1. The required NVA 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. This is a required accuracy. The NVA was tested with 390 checkpoints located in bare earth and urban (non-vegetated) areas.

2. Vegetated Vertical Accuracy (VVA): VVA shall be reported for "tall weeds" land cover classes. The target VVA is: 29.4 cm at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for LiDAR Data, i.e., based on the 95th percentile error in all vegetated land cover classes combined. This is a target accuracy. The VVA was tested with 272 checkpoints located in forested and tall weeds (vegetated) areas. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. 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 0.090 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 390 independent checkpoints located in Bare Earth and Urban land cover classes.

Tested 0.089 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 DEM was calculated using 390 independent checkpoints located in the Bare Earth and Urban land cover categories.

Tested 0.283 meters VVA was calculated using 272 checkpoints located in the Forested and Tall Weeds land cover categories at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for LiDAR Data. Tested against the DEM.

All files are inspected to ensure that they conform to the specified file naming conventions, all files load in their correct geographic position, all files conform to the project specifications for file standard and content.

Data cover the entire area specified for this project.

Data is backed up to tape and to cloud storage.