2016 USGS Lidar: Maine QL2

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

Geographic Extent: Four partial counties in western Maine, covering approximately 5,034 total square miles

Dataset Description: Maine 2016 QL2 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 was developed based on a horizontal projection/datum of NAD83 (2011) UTM Zone 19, meters and vertical datum of NAVD1988 (Geoid 12B), meters. Lidar data was delivered as flightline-extent unclassified LAS swaths, as processed Classified LAS files formatted to 6,115 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 schema. Continuous breaklines were produced in Esri file geodatabase format. Continuous contours with an interval of 1 foot were created in Esri file geodatabase format.

Ground Conditions: Lidar was collected in spring of 2016, 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 101 ground control points that were used to calibrate the lidar to known ground locations established throughout the Maine project area. An additional 205 independent accuracy checkpoints, 118 in Bare Earth and Urban landcovers (118 NVA points), 87 in Forested, Brushland/Trees, and Tall Weeds/Crops categories (87 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data. In addition to the lidar point data, bare earth Digital Elevation Models (DEMs), at a 1 m grid spacing, created from the lidar point data are also available. These data are available for download here: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=6267 Breaklines created from the lidar area also available for download in either gdb or gpkg format at: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/6264/breaklines The DEM and breakline 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, OCM or its partners.

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, hydro-flattened DEMs, and contours as necessary.

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The following reports are available for this data set: 1. Maine 2016 QL2 Lidar Project Report: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/6264/supplemental/me2016_usgs_me_ql2_m6264_lidar_report.pdf 2. Maine 2016 QL2 Lidar Project Report Appendices: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/6264/supplemental/me2016_usgs_me_ql2_m6264_lidar_report_app.pdf 3. Quantum Spatial FOCUS Report: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/6264/supplemental/me2016_usgs_me_ql2_m6264_lidar_focus_report.pdf

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

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

"ldrsens" : "Leica_ALS70",

"ldrmaxnr" : "4",

"ldrnps" : "0.67",

"ldrdens" : "2.21",

"ldranps" : "0.67",

"ldradens" : "2.21",

"ldrfltht" : "2100",

"ldrfltsp" : "150",

"ldrscana" : "40.0",

"ldrscanr" : "53.4",

"ldrpulsr" : "260.40",

"ldrpulsd" : "4",

"ldrpulsw" : "0.48",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1528.67",

"ldrswato" : "10.67",

"ldrgeoid" : "g2012bu0.bin"

},

"ldrinfo_MESP" : {

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

"ldrsens" : "Leica_ALS70_MESP",

"ldrmaxnr" : "4",

"ldrnps" : "0.56",

"ldrdens" : "3.18",

"ldranps" : "0.56",

"ldradens" : "3.18",

"ldrfltht" : "1925",

"ldrfltsp" : "150",

"ldrscana" : "34.0",

"ldrscanr" : "57.3",

"ldrpulsr" : "288.60",

"ldrpulsd" : "4",

"ldrpulsw" : "0.44",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1177.06",

"ldrswato" : "16.84",

"ldrgeoid" : "g2012bu0.bin"

},

"ldraccur" : {

"ldrchacc" : "0.196",

"rawnva" : "0.114",

"rawnvan" : "116"

},

"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" : "In-land 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., the U.S. Geological Survey (USGS), the Maine Office of GIS, NOAA, the NOAA Office for Coastal Management (OCM) or its partners.

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=6264;

No restrictions apply to this data.

None. However, users should be aware that temporal changes may have occurred since this dataset 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 its limitations. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.

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 116 of 118 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.

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 118 checkpoints located in bare earth and urban (non-vegetated) areas. 2. Vegetated Vertical Accuracy (VVA): VVA shall be reported for "forested", "brushland/trees", and "tall weeds/crops" 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 87 checkpoints located in forested, brushland/trees, and tall weeds/crops (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.; Quantitative Value: 0.114 meters, Test that produced the value: Tested 0.114 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 116 independent checkpoints located in Bare Earth and Urban land cover classes.; Quantitative Value: 0.113 meters, Test that produced the value: Tested 0.113 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 118 independent checkpoints located in the Bare Earth and Urban land cover categories.; Quantitative Value: 0.253 meters, Test that produced the value: Tested 0.253 meters VVA was calculated using 87 checkpoints located in the Forested, Brushland/Trees, and Tall Weeds/Crops land cover categories at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for Lidar Data. Tested against the DEM.

These raw LAS and LAS data files include all data points collected. No points have been removed or excluded. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications. Datasets contain complete coverage of tiles. A visual qualitative assessment was performed to ensure data completeness. There are no void areas or missing data. 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 covers the entire area specified for this project.