Data Management Plan

LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. By positioning laser range

finding with the use of 1 second GPS with 100hz inertial measurement unit corrections, Terrapoint's LIDAR instruments are able to make

highly detailed geospatial elevation products of the ground, man-made structures and vegetation. These data were collected from

March 29 - April 6, 2007 for Gloucester County, New Jersey. The project area covers 353 square miles. The LiDAR flightlines for this

project were planned for a 50% acquisition overlap. The nominal resolution of this project without overlap is 1.25 m. Four returns were

recorded for each pulse in addition to an intensity value. GPS Week Time, Intensity, Flightline and number attributes were provided for

each LiDAR point. Data is provided as random points, in LAS v1.1 format, classified according to the following ASPRS Class Codes:

Class 1 - Non-ground

Class 2 - Ground

Class 7 - Noise

Class 9 - Water

Original contact information:

Contact Name: Claude Vickers

Contact Org: Terrapoint USA

Title: Production Manager

Phone: 1-877-80-TERRA

Email: claude.vickers@terrapoint.com

Process Steps:

• 2007-04-01 00:00:00 - General Overview: Project Area = 874 square kilometers, Type of Scanner = Optech 3100EA, Number of Scanners = 1, Data Acquisition Height = 1550 meters, AGL Scanner Field of View = 46 degrees, The scan frequency = 30 Hertz, Pulse Repetition Rate = 71 Kilohertz, Aircraft Speed = 150 Knots, Swath Width = 1315 m, Nominal Ground Sample Distance = 1.25 meters - no overlap, Number of Returns Per Pulse = 4, Distance Between Flight Lines = 658 m, The Airborne LiDAR survey was conducted using one OPTECH 3100EA system flying at a nominal height of 1550 metres AGL, a total angular coverage of 46 degrees. Flight line spacing nominally 658 meters providing overlap of 50% on adjacent flight lines. Lines were flown in NE/SW to best optimize flying time considering the layout for the project. The aircraft used for this survey was a Piper Navajo, registration C-GPJT. This aircraft has a flight range of approximately 6 hours and was flown at an average altitude of 1550 meters above ground level (AGL). The aircraft was staged from the Millville Airport and ferried daily to the project site for flight operations. GPS Receivers: A combination of Sokkia GSR 2600 and Applanix POSAv-510 dual frequency GPS receivers were used to support the airborne operations of this survey and to establish the GPS control network. Number of Flights and Flight Lines: A total of 8 missions were flown for this project with flight time ranging approximately 15 hours under good meteorological and GPS conditions. 76 flight lines were flown over the project site to provide complete coverage. Reference Coordinate System Used Existing NGS (National Geodetic Survey) monuments were observed in a GPS control network to establish 1 new station(s): Station_ID: 128U-01128U-01 was used as primary control for the project flight missions and kinematic ground surveys. The published horizontal datum of the NGS stations is NAD83 and the vertical datum NAVD88. The following are the final coordinates of the newly established control points used in this project: Station_ID: 128U-01, West_Longitude: 75 09 04.89385, North_Latitude: 39 43 09.54246, Ellips_Elev: 14.761 m, Geoid Model Used: The Geoid03 geoid model, published by the NGS, was used to transform all ellipsoidal heights to orthometric.
• 2007-11-01 00:00:00 - Airborne GPS Kinematic Airborne GPS kinematic data was processed on-site using GrafNav kinematic On-The-Fly (OTF) software. Flights were flown with a minimum of 6 satellites in view (13o above the horizon) and with a PDOP of better than 3.5. Distances from base station to aircraft were kept to a maximum of 30 km, to ensure a strong OTF (On-The-Fly) solution. For all flights,the GPS data can be classified as excellent, with GPS residuals of 5 cm average but no larger than 10 cm being recorded. Generation and Calibration of laser points (raw data) The initial step of calibration is to verify availability and status of all needed GPS and Laser data against field notes and compile any data if not complete. Subsequently the mission points are output using Optech's Dashmap, initially with default values from Optech or the last mission calibrated for system. The initial point generation for each mission calibration is verified within Microstation/Terrascan for calibration errors. If a calibration error greater than specification is observed within the mission, the roll pitch and scanner scale corrections that need to be applied are calculated. The missions with the new calibration values are regenerated and validated internally once again to ensure quality. All missions are validated against the adjoining missions for relative vertical biases and collected GPS kinematic ground truthing points for absolute vertical accuracy purposes. On a project level, a coverage check is carried out to ensure no slivers are present. Data Classification and Editing The data was processed using the software TerraScan, and followed the methodology described herein. The initial step is the setup of the TerraScan project, which is done by importing client provided tile boundary index (converted to the native UTM zone for processing) encompassing the entire project areas. The 3D laser point clouds, in binary format, were imported into the TerraScan project and divided in 440 tiles in LAS 1.0 format. Once tiled, the laser points were classified using a proprietary routine in TerraScan. This routine removes any obvious outliers from the dataset following which the ground layer is extracted from the point cloud. The ground extraction process encompassed in this routine takes place by building an iterative surface model. This surface model is generated using three main parameters: building size, iteration angle and iteration distance. The initial model is based on low points being selected by a "roaming window" with the assumption that these are the ground points. The size of this roaming window is determined by the building size parameter. The low points are triangulated and the remaining points are evaluated and subsequently added to the model if they meet the iteration angle and distance constraints. This process is repeated until no additional points are added within an iteration. A second critical parameter is the maximum terrain angle constraint,which determines the maximum terrain angle allowed within the classification model. The data is then manually quality controlled with the use of hillshading, cross-sections and profiles. Any points found to be of class vegetation, building or error during the quality control process, are removed from the ground model and placed on the appropriate layer. An integrity check is also performed simultaneously to verify that ground features such as rock cuts, elevated roads and crests are present. Once data has been cleaned and complete, it is then reviewed by a supervisor via manual inspection and through the use of a hillshade mosaic of the entire project area. Deliverable Tiling Scheme All files were converted to LAS 1.1, in the specified projection and units and were delivered in the client provided tiling scheme with a total of 440 tiles.
• 2010-08-01 00:00:00 - The NOAA Office for Coastal Management (OCM) received the files in las format. The files contained Lidar elevation and intensity measurements. The data were in New Jersey State Plane projection, and NAVD88 Geoid 03 vertical datum.OCM performed the following processing to the data to make it available within the Digital Coast: 1. The data were converted from New Jersey State Plane coordinates to geographic coordinates. 2. The data were converted from NAVD88 (orthometric) heights to GRS80 (ellipsoid) heights using Geoid 03. 3. The LAS data were sorted by latitude and the headers were updated.

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer;