2014 USGS CMGP Lidar: Sandy Restoration (Delaware and Maryland)

Geographic Extent: SANDY_Restoration_DE_MD_QL2 Area of Interest covers approximately 3.096 square miles. Lot #5 contains the full project area

Dataset Description: The SANDY_Restoration_DE_MD_QL2 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 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LIDAR Specification, Version 1. The data was developed based on a horizontal projection/datum of UTM Zone 18 North, NAD83, meters and vertical datum of NAVD1988 (GEOID12A), meters. LiDAR data was delivered in RAW flight line swath format, processed to create Classified LAS 1.2 Files formatted to 3842 individual 1500m x 1500m tiles, and corresponding Intensity Images and Bare Earth DEMs tiled to the same 1500m x 1500m schema, and Breaklines in ESRI Shapefile format.

Ground Conditions: LiDAR was collected in Winter 2013 / Spring 2014, 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, Quantum Spatial established a total of 78 QA control points and 99 Land Cover control points that were used to calibrate the LIDAR to known ground locations established throughout the SANDY_Restoration_DE_MD_QL2 project area.

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 hydro-flattened Digital Elevation Model (DEM) 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 as necessary.

USGS Contract No. G10PC00025

CONTRACTOR: Quantum Spatial, Inc

Ground Control Points were acquired and calibrated by Compass Data, Inc.

All Lidar data acquisition, calibration, and follow-on processing were completed by the prime contractor.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Lidar Specification v1.0",

"ldrsens" : "Leica ALS 70",

"ldrmaxnr" : "4",

"ldrnps" : "0.69",

"ldrdens" : "1.35",

"ldrfltht" : "1676",

"ldrfltsp" : "150",

"ldrscana" : "17",

"ldrscanr" : "31.7",

"ldrpulsr" : "165.6",

"ldrpulsd" : "4",

"ldrpulsw" : "0.38",

"ldrwavel" : "1064",

"ldrmpia" : "0",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1024.81",

"ldrswato" : "12.49%",

"ldrcrs" : "NAD_1983_UTM_Zone_18N_meters",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12A"

},

"ldraccur" : {

"ldrchacc" : "1",

"rawfva" : "0.162",

"clsfva" : "0.123",

"clscva" : "0.141",

"clssvas" : {

"svalctyp" : "Forested, Fully Covered by Trees",

"svavalue" : "0.528"

},

"clssvas" : {

"svalctyp" : "High Grass, Weeds, and Crops",

"svavalue" : "0.146"

},

"clssvas" : {

"svalctyp" : "Urban Areas",

"svavalue" : "0.122"

}

},

"lasinfo" : {

"lasver" : "1.2",

"lasprf" : "1",

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

"lasolap" : "Swath "overage" points were identified in these files by adding 16 to the standard classification values.",

"lasintr" : "8",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare earth ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "In-land Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "11",

"clasitem" : "Withheld"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Overlap Default (Unclassified)"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "Overlap Bare-earth ground"

},

"lasclass" : {

"clascode" : "25",

"clasitem" : "Overlap In-land Water"

}

}}

LiDAR points in LAS format (ASPRS Classes 1,2,7,9,10,17,18)

none

Any conclusions drawn from the analysis of this information are not the responsibility of Quantum Spatial, USGS, NOAA, the Office for Coastal Management or its partners.

Data is available online for bulk or 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.

MicroStation Version 8; TerraScan Version 14; TerraModeler Version 14; GeoCue Version 2013.1.45.1; ESRI ArcGIS 10.1; Global Mapper 13; ALS Post Processor 2.75 Build #25; Windows 7 Operating System \\psihq_nx3200\Projects\Projects\15247_Sandy_Restoration_DE_MD_USGS 66.5 GB and \\Matrix\matrix\LIDAR\15247_Sandy_Restoration_DE_MD 3.84 TB

The specifications require that only Fundamental Vertical Accuracy (FVA) be computed for raw lidar point cloud swath files.

The vertical accuracy value is the AccuracyZ at 95 percent Confidence Interval in meters. The FVA was tested using 20 of 99 independent survey located in open terrain. The survey checkpoints were distributed throughout the project area. The 20 of 99 independent check points 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. AccuracyZ has been tested to meet 18.13 cm Fundamental Vertical Accuracy at 95 Percent 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: 0.162, Test that produced the value:

The FVA was tested using 20 of 99 independent survey located in open terrain in Lot #5. The survey checkpoints were distributed throughout the project area. The 20 of 99 independent check points 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. The RMSE was computed to be 0.162. AccuracyZ has been tested to meet 18.13 cm Fundamental Vertical Accuracy at 95 Percent 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.

Datasets contain complete coverage of tiles.

No points have been removed or excluded.

A visual qualitative assessment was performed to ensure data completeness.

There are no void areas or missing data. The raw point cloud is of good quality and data passes Fundamental Vertical Accuracy specifications.

Classified LAS files were tested by Photo Science for both vertical and horizontal accuracy. All data is seamless from one tile to the next, no gaps or no data areas.

Data is backed up to tape and to cloud storage.