2017 Lidar: Eastern Maine

Product: These LiDAR data are processed classified LAS 1.4 files, formatted to 10,142 individual 1,500-meter x 1,500-meter tiles; used to create intensity images, 3D breaklines and hydro-flattened DEMs as necessary.

Geographic Extent: Six partial counties in Maine, covering approximately 8736 total square miles.

Dataset Description: Maine 2017 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 for counties in the eastern AOI was developed based on a horizontal projection/datum of NAD83 (2011) UTM Zone 19, meters and vertical datum of NAVD88 (GEOID12B), meters. LiDAR data was delivered as flightline-extent unclassified LAS swaths, as processed Classified LAS 1.4 files formatted to 10,142 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 hydro-flattened breaklines were produced in Esri file geodatabase format.

Ground Conditions: LiDAR was collected in the spring and fall of 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, Quantum Spatial, Inc. established a total of 176 ground control points that were used to calibrate the LiDAR to known ground locations established throughout the project area. An additional 299 independent accuracy checkpoints, 176 in Bare Earth and Urban landcovers (176 NVA points), 123 in Forested, Shrubs, and Tall Weeds categories (123 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 2 blocks from this USGS site:

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_ME_Eastern_B1_2017_LAS_2019/ and USGS_LPC_ME_Eastern_B2_2017_LAS_2019 and processed the data to the Data Access Viewer (DAV) and https. The number of files downloaded was 10,142.

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.

State of Maine DO#: DO 18B 20170322000000008328 MPA#: MA 18P 16041900000000000157. CONTRACTOR: Quantum Spatial, Inc. SUBCONTRACTOR: Keystone Aerial Surveys, Inc. and Aeroptic, LLC. LiDAR data were acquired by Quantum Spatial, Inc., Keystone Aerial Surveys, Inc., and Aeroptic, LLC. All follow-on processing was completed by the prime contractor.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

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

"ldrsens" : "Leica ALS 70",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.61",

"ldrdens" : "2.21",

"ldranps" : "0.61",

"ldradens" : "2.21",

"ldrfltht" : "2100",

"ldrfltsp" : "140",

"ldrscana" : "36",

"ldrscanr" : "56",

"ldrpulsr" : "262.6",

"ldrpulsd" : "4",

"ldrpulsw" : "0.22",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1364.66",

"ldrswato" : "30",

"ldrgeoid" : "GEOID12B",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 19 Meters"

},

"ldrinfo_2" : {

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

"ldrsens" : "Leica ALS 80",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.61",

"ldrdens" : "2.21",

"ldranps" : "0.61",

"ldradens" : "2.21",

"ldrfltht" : "2478",

"ldrfltsp" : "140",

"ldrscana" : "36",

"ldrscanr" : "33.5",

"ldrpulsr" : "484",

"ldrpulsd" : "3",

"ldrpulsw" : "0.25",

"ldrwavel" : "1064",

"ldrmpia" : "0",

"ldrbmdiv" : "0.25",

"ldrswatw" : "1610.30",

"ldrswato" : "30",

"ldrgeoid" : "GEOID12B",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 19 Meters"

},

"ldrinfo_3" : {

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

"ldrsens" : "Riegl 1560i",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.70",

"ldrdens" : "2.03",

"ldranps" : "0.70",

"ldradens" : "2.03",

"ldrfltht" : "1829",

"ldrfltsp" : "150",

"ldrscana" : "58.52",

"ldrscanr" : "210",

"ldrpulsr" : "700",

"ldrpulsd" : "3",

"ldrpulsw" : "0.25",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.25",

"ldrswatw" : "2049",

"ldrswato" : "30",

"ldrgeoid" : "GEOID12B",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 19 Meters"

},

"ldraccur" : {

"ldrchacc" : "0.196",

"rawnva" : "0.100",

"rawnvan" : "176"

},

"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"

}

}}

In no event shall the creators, custodians, or distributors of these data be liable for any damages arising out of its use, or from the inability of the customer to use these data for their intended application.

Any conclusions drawn from the analysis of this information are not the responsibility of the State of Maine, 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 176 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.

Non Vegetated Accuracy (NVA) = 9.9 cm or 5 cm RMSE

Vegetated Vertical Accuracy (VVA) = 25.5 cm

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.