2014 USGS CMGP Lidar: Post Sandy (Long Island, NY)

TASK NAME: Long Island New York Sandy LIDAR

lidar Data Acquisition and Processing Production Task

USGS Contract No. G10PC00057

Task Order No. G14PD00296

Woolpert Order No. 074257

CONTRACTOR: Woolpert, Inc.

This data set is comprised of lidar point cloud data, raster DEM, hydrologic 3-d breaklines, raster intensity, survey control, project tile index, and project data extent. This task order requires lidar data to be acquired over two counties in New York State; Suffolk and Nassau. The total area of the Long Island Sandy Lidar AOI is approximately 1,225 square miles. The lidar data will be acquired and processed under the requirements identified in this task order. lidar data is a remotely sensed high resolution elevation data collected by an airborne platform. The lidar sensor uses a combination of laser range finding, GPS positioning, and inertial measurement technologies. The lidar systems collect data point clouds that are used to produce highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures, and vegetation. The task required the LiDAR data to be collected at a nominal pulse spacing (NPS) of 0.7 meters. The final products include classified LAS, one (1) meter pixel raster DEMs of the bare-earth surface in ERDAS IMG Format, and 8-bit intensity images. Each LAS file contains lidar point information, which has been calibrated, controlled, and classified. Additional deliverables include hydrologic breakline data, control data, tile index, lidar processing and survey reports in PDF format, FGDC metadata files for each data deliverable in .xml format, and LAS swath data. Collected swath files that were that were larger than 2GB were provided in multiple sub-swath files, each less than 2GB. Ground conditions: Water at normal levels; no unusual inundation; no snow; leaf off. The tide window requirements for the lidar data acquisition; Tidally impacted waters within the AOI are expected to be acquired at Predicted MLW +- 2 hours exclusive of neap tide.; The bare earth DEMs along the coast may have a variance in the water heights due to temporal differences during the lidar data acquisition and will be represented in DEM as a seam-like anomaly.; One coastal elevation was applied to entire project area. Due to differing acquisition dates and thus differing tide levels there will be areas in the DEM exhibiting what appears to be "digging" water features. Sometimes as much as approximately 1 meter. This was done to ensure that no coastal hydro feature was "floating" above ground surface.; During Hydrologic breakline collection, Woolpert excluded obvious above-water piers or pier-like structures from the breakline placement. Some features extend beyond the apparent coastline and are constructed in a manner that can be considered an extension of the ground. These features were treated as ground during classification and subsequent hydrologic delineation. In all cases, professional practice was applied to delineate what appeared to be the coast based on data from multiple sources; Due to the many substructures and the complexity of the urban environment, interpolation and apparent "divots" (caused by tinning) may be evident in the surface of the bare earth DEM. In all cases, professional practice was applied to best represent the topography.

Original contact information:

Contact Org: Woolpert

Phone: (937) 461-5660

The lidar data will be acquired and processed under the requirements identified in this task order. This data will assist in the evaluation of storm damage and erosion of the local environment as part of USGS' Hurricane Sandy response.

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A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/4938/supplemental/ny2014_usgs_cmgp_sandy_longisland_m4938.kmz

The overall lidar report for this project is available at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/4938/supplemental/ny2014_usgs_cmgp_sandy_longisland_m4938_lidarreport.pdf

The survey report for this project is available at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/4938/supplemental/ny2014_usgs_cmgp_sandy_longisland_m4938_surveyreport.pdf

The processing report for this project is available at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/4938/supplemental/ny2014_usgs_cmgp_sandy_longisland_m4938_processingreport.pdf

Files in LAZ format (Classifications 1,2,7,9,10)

none

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the National Geodetic Survey, the Office for Coastal Management, or its partners.

This data can be obtained on-line at the following URL:

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=4938;

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.

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.

Compiled to meet 0.42 meters horizontal accuracy at 95 percent confidence level. Lidar system specifications are available in the project report.

LAS data covering the Long Island Sandy Recovery Lidar Task Order was compared to independent survey control points to determine the FVA of the LAS Swath and of the Bare-Earth DEM. In addition, this LAS data was compared to independent supplemental points from categories: Urban, Tall Weeds/Crops, Brush Lands and Trees, and Forested/Fully Grown.

Fundamental Vertical Accuracy (FVA)

LAS Swath Fundamental Vertical Accuracy (FVA) Tested 0.113 meters fundamental vertical accuracy at a 95 percent confidence level, derived according to NSSDA, in open terrain using (RMSEz) x 1.96000 asdefined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the TIN.

Bare-Earth DEM Fundamental Vertical Accuracy (FVA) Tested 0.115 meters fundamental vertical accuracy at a 95 percent confidence level, derived according to NSSDA, in open terrain using (RMSEz) x 1.96000 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the DEM.

Supplemental Vertical Accuracy (SVA)

Urban Land Cover Classification Supplemental Vertical Accuracy (SVA) tested 0.140 meters at the 95th percentile using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the DEM.

Tall Weeds/Crops Land Cover Classification Supplemental Vertical Accuracy (SVA) tested 0.150 meters at the 95th percentile using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the DEM.

Brush Lands and Trees Land Cover Classification Supplemental Vertical Accuracy (SVA) tested 0.250 meters at the 95th percentile using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the DEM.

Forested and Fully Grown Land Cover Classification Supplemental Vertical Accuracy (SVA) tested 0.160 meters at the 95th percentile using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the DEM.

Consolidated Vertical Accuracy (CVA)

Tested 0.186 meters at the 95th percentile level using National Digital Elevation Program (NDEP)/ASPRS Guidelines and tested against the DEM. CVA is based on the 95th percentile error in all land cover categories combined.

The lidar data is visually inspected for completeness to ensure that are no void areas or missing data.

All formatted data cover the entire area specified for this project and are validated using a combination of commercial lidar processing software, GIS software, and proprietary programs to ensure proper formatting and loading prior to delivery.