Data Management Plan

The Light Detection and Ranging (LiDAR) dataset is a survey of the Seneca NY Watershed project area. The entire survey area for Seneca encompasses approximately 1638 square miles. The LiDAR point cloud was flown at a nominal post spacing of 1.5 meters for unobscured areas. The LiDAR data and derivative products produced are in compliance with the U.S. Geological Survey National Geospatial Program LIDAR Base Specifications, Version 1.0. The flight lines were acquired by Northrop Grumman Corporation and Digital Aerial Solutions (DAS) and the data was post processed by Northrop GrummanAdvanced GEOINT Solutions Operating Unit (AGSOU), which was flown over twelve missions from May 5,2012-May 6,2012, November 19,2013-November 21,2013, April 17,2014-April 24,2014, June 15,2014. Derivative products from the aerial acquisition include: raw point cloud data in LAS v1.2 format, classified point cloud data in LAS v1.2 format, bare earth surface (raster DEM) tiles in 32-bit floating point raster ERDAS .IMG format, breaklines in ESRI Arc Shape format, control points in ESRI Arc Shape format, project report, and FGDC compliant XML metadata.

Process Steps:

• 2014-04-24 00:00:00 - The ABGPS, inertial measurement unit (IMU), and raw scans are collected during the LiDAR aerial survey. The ABGPS monitors the xyz position of the sensor and the IMU monitors the orientation. During the aerial survey, laser pulses reflected from features on the ground surface are detected by the receiver optics and collected by the data logger. GPS locations are based on data collected by receivers on the aircraft and base stations on the ground. The ground base stations are placed no more than 40 km radius from the flight survey area.
• 2014-05-05 00:00:00 - The ABGPS, IMU, and raw scans are integrated using proprietary software developed by the airborne sensor manufacturer and delivered with each of the two sensors used on this project the Optech System and the Leica System. The resultant file is in a LAS binary file format. The LAS version 1.2 file format can be easily transferred from one file format to another. It is a binary file format that maintains information specific to the LiDAR data (return number, intensity value, xyz, etc.). The resultant points are produced in the NAD83 UTM 18 North Coordinate System, with units in Meters and referenced to the NAVD88 datum. The LiDAR mass points were processed in American Society for Photogrammetry and Remote Sensing LAS 1.2 format. The header file for each dataset is complete as defined by the LAS 1.2 specification. The datasets were divided into a 1500 meter by 1500 meter tiling scheme, named according to the US National Grid scheme. The tiles are contiguous, do not overlap, and are suitable for seamless topographic data mosaics that include no "no data" areas. The names of the tiles include numeric column and row designations and all files utilize the LAS file extension
• 2014-06-10 00:00:00 - The unedited data are classified to facilitate the application of the appropriate feature extraction filters. A combination of proprietary filters are applied as appropriate for the production of bare earth digital elevation models (DEMs). Interactive editing methods are applied to those areas where it is inappropriate or impossible to use the feature extraction filters, based upon the design criteria and/or limitations of the relevant filters. These same feature extraction filters are used to produce elevation height surfaces.
• 2014-06-18 00:00:00 - Filtered and edited data are subjected to rigorous QA/QC, according to the Northrop Grumman, Advanced GEOINT Solutions Operating Unit Quality Control Plan and Procedures. A series of quantitative and visual procedures are employed to validate the accuracy and consistency of the filtered and edited data. Ground control is established by Northrop Grumman, Advanced GEOINT Solutions Operating Unit and GPS-derived ground control points (GCPs) in various areas of dominant and prescribed land cover. These points are coded according to land cover, surface material, and ground control suitability. A suitable number of points are selected for calculation of a statistically significant accuracy assessment, as per the requirements of the National Standard for Spatial Data Accuracy. A spatial proximity analysis is used to select edited LiDAR data points within a specified distance of the relevant GCPs. A search radius decision rule is applied with consideration of terrain complexity, cumulative error, and adequate sample size. Accuracy validation and evaluation is accomplished using proprietary software to apply relevant statistical routines for calculation of Root Mean Square Error (RMSE) and the National Standard for Spatial Data Accuracy (NSSDA), according to Federal Geographic Data Committee (FGDC) specifications.
• 2014-06-18 00:00:00 - The Bare Earth DEM was extracted from the raw LIDAR products and attributed with the bare earth elevation for each cell of the DEM. Bare Earth DEMs do not include buildings, vegetation, bridges or overpass structures in the bare earth model. Where abutments were clearly delineated, this transition occurred at the junction of the bridge and abutment. Where this junction was not clear, the extractor used their best estimate to delineate the separation of ground from elevated bridge surface. In the case of bridges over water bodies, if the abutment was not visible, the junction was biased to the prevailing stream bank so as not to impede the flow of water in a hydrographic model. Bare earth surface includes the top of water bodies not underwater terrain, if visible.
• The NOAA Office for Coastal Management (OCM) downloaded 2177 laz files from the USGS' rockyFTP website. The files contained elevation and intensity measurements for the project area. The data were in UTM Zone 18, NAD 1983 (2011), meters coordinates and NAVD88 (Geoid12B) elevations in meters. The data were classified as: 1 - Unclassified, 2 - Ground, 7 - Noise, 9 - Water, 10 - Ignored Ground, 11 - Withheld, 17 - Overlap Default, 18 - Overlap Ground. The NOAA Office for Coastal Management processed all classifications of points to the Digital Coast Data Access Viewer (DAV). OCM performed the following processing on the data for Digital Coast storage and provisioning purposes: 1. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges. 2. Internal OCM scripts were run on the laz files to convert from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid 12B model, to convert from UTM Zone 17, NAD 1983 (2011), meters coordinates to geographic coordinates, to assign the geokeys, to sort the data by gps time and zip the data to database and to http.

Data is available online for bulk or custom downloads

Data is backed up to tape and to cloud storage.