Data Management Plan

In the fall of 2006, Sanborn Map Company was contracted by Camp Dresser McKee, Inc (CDM) to execute a LiDAR (Light Detection and Ranging) survey campaign in the state of Maine. LiDAR data in the form of 3-dimensional positions

of a dense set of masspoints was collected for the 584 sqaure miles of Cumberland and York Counties. This data was used in the development of the bare-earth-classified elevation point data sets. The Leica ALS-50 LiDAR system

was used to collect data for the whole survey campaign. The LiDAR system is calibrated by conducting flight passes over a known ground surface before and after each LiDAR mission. During final data processing, the calibration

parameters are inserted into post-processing software.

Six airborne GPS (Global Positioning System) base stations were used in this project. A new point was set at the Portland Airport (501) The other base stations were set up at National Geodetic Survey (NGS) markers. NGS Monuments

901- PID: OC0229 and 801 - PID: OC0230 are located at the Biddeford Airport. The other existing NGS monuments used in the network are point 701 - PID: AJ2697, located on Bailey Island, point 702 - PID: OC0429, located at Fort

Constitution, and point 703 - PID: OC0478 located southeast of York Beach were tied to the other three points to create a GPS survey network. The coordinates of these stations were checked against each other with the three

dimensional GPS baseline created at the airborne support set up and determined to be within project specifications.

Leica ALS-50 LiDAR Scanner Parameters:

Pulse Rate: 50,000 hertz

Scan Frequency: 36 hertz

Scan Width (Half Angle): 18 degrees

Flying Height: 1,200 meters above ground level

Flying Speed: ~120 knots

Process Steps:

• 2007-02-13 00:00:00 - Using the Leica ALS-50 Light Detection and Ranging (LiDAR) system, flight lines were planned for standard density 1.4 meter GSD. The Flight plan for the project includes the following specifications to fully meet the project requirements - single pass density of approximately 1.4 square meters per sample * Swath width ~688 meters * Flight altitude 1200 meters * flight line spacing ~516 meters with ~125 meters overlap *Scan Frequency- 36 Hz *Scan Angle- 16 degrees * Aircraft ground speed -- 120 knots * System Calibration pre and post mission * Two GPS base stations within 30 KM. Multiple returns were recorded for each laser pulse along with an intensity value for each return. The data are calibrated for geographic referencing. Points are further processed, using TerraSolid software, to classify return values. The first and last return data is filtered to remove the vegetation and above ground manmade features to yield a ground surface.
• 2013-04-01 00:00:00 - The NOAA Office for Coastal Management (OCM) received topographic files in LAS format. The files contained lidar elevation and intensity measurements. The data were received in UTM Zone 19N (NAD83) coordinates and were vertically referenced to NAVD88 using the Geoid03 model. The vertical units of the data were meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The topographic las files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid03. 2. The topographic las files were converted from a Projected Coordinate System (UTm 19N) to a Geographic Coordinate system (GCS). 3. The topographic las files' horizontal units were converted from meters to decimal degrees.

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

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=2479

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