Data Management Plan

In early October 2004, LIDAR was flown for Burlington and Camden Counties. The acquisition is being sponsored FEMA because of the July flood. It will be delivered to Dewberry & Associates for QAQC in January and should be released to partners in April. The LIDAR data will contain elevation information capable of generating 2 ft contour intervals.

Light Detection and Ranging (LIDAR) is a method of locating objects on the ground using aerial-borne equipment. It is similar to RADAR or SONAR in that the two-way travel time of an energy beam reflected off an object is precisely measured, but this technology uses laser light instead of radio or sound waves. This technology has proven very useful in remote sensing of the earth. It can be used for determining elevations of both the earth's surface and items (natural and man-made) on the surface. Analysis of LIDAR data is used in detailed modeling of the earth's surface for drainage and floodplain studies, determining how a new structure will affect views from various locations, shoreline erosion studies, and other reasons. This data set contains only the bare earth mass points. Bare earth points represent ground features. Features that are above ground, such as buildings, bridges, tree tops, etc, have been eliminated. Mass points may appear to have "holes" with no elevation values in areas where the surface could not be determined, such as very dense forests or urban areas.

Process Steps:

• LIDAR Data Acquisition. The Sanborn Map Company, Inc. flew the project area with the LIDAR sensor. Where overlaps between the two series of data occurred, the newer data was used. No attempt at blending the two datasets was made to maintain the highest data integrity. In an effort to permit correlation of the point values with tidal gauge stations, the Sanborn Map Company, Inc. was required to fly tidal shoreline areas during the low tide cycle (slack water - low tide - slack water) as predicted by local tide stations. The LIDAR sensor collected raw data that was referenced in UTM. The flight plan on this project included the following specifications to meet the project requirements: *Single pass density - 1.696 square meters per sample; *Average area sampling density -1.272 square meters per sample; *Swath width - 996.76 meters; *Flight altitude -1371 meters (4500 ft); *Flight line spacing - 498.38 meters w/50% overlap; *Scan frequency - 21 Hz; *Firing rate - 25 kHz; *Scan angle - 20 degrees; *Ground speed - 140 knots. When complete, the raw data was delivered to Spatial Systems.
• LIDAR Data Processing. Computational Consulting Systems. The First and Last Return data was delivered to CCS in large blocks of data. CCS processed the data using both the First and Last Returns, removed artifacts using automated and manual techniques, and reprojected the data into the client-specified X, Y, Z text files using the 1200 meter x 1800 meter tiles, NAD 83 meters, NAVD 88 meters. CCS also generated the Intensity Imagery using the client-specified USGS 3.75' tiling scheme. The data products were delivered to SSA for quality assurance testing, formatting and final delivery.
• LIDAR Data Post Processing. Spatial Systems Associates. SSA digitized the shoreline from the Intensity Imagery for the purposes of delineating a shoreline. Any LIDAR points that fell seaward of this shoreline were assigned the value of zero (0). In addition to the shoreline, SSA delineated upland ponds using the same technique and assigned all LIDAR points that fell within the water area the value of the lowest observed point close to the shore. The observed elevation values were not lost - a fourth field in the data file was added for the assigned value. SSA also performed a variety of QA procedures to determine if the point density was within expected ranges; that each tile was completely filled; that all tiles were accounted for, and that the tiles were named in accordance with client specifications.
• LIDAR Data Check Point Surveys. NXL Construction Services. NXL was contracted to acquire the check-points in the 5 different land cover classes. SSA provided NXL with maps of each area where a check-point was to be located. The points were scattered throughout the project area. NXL was permitted the latitude to select the exact location based on field conditions, provided the points were generally within a 1 mile radius of the chosen location and that the land cover class was the same as the one specified. The land cover classes were: Grass/Ground, High Grass/Crops, Brush/Low Trees, Forest, and Urban/Pavement.
• LIDAR Data Quality Assurance. Dewberry LLC was provided with the check-point and LIDAR Bare Earth Mass Points data to perform their independent quality assurance work. They performed detailed analyses to determine if the vertical accuracy was within specifications and examined the data for flight, data collection and processing inconsistencies. Neither the flight vendor (Airborne 1) nor the processing vendor (CCS) was given access to the check-point data. The entire accuracy report can be found at http://dnrweb.dnr.state.md.us/gis/data/lidar.
• 2016-03-05 00:00:00 - The NOAA Office for Coastal Management (OCM) received LAS files containing the point cloud elevation data from FEMA in a bulk delivery on a HDD. OCM performed the following processing on the data: 1. Converted from State Plane (feet) to Geographics coordinates (decimal degrees). 2. Converted from NAVD88 heights (feet) to ellipsoidal heights with Geoid03. 3. Reclassified points 3 and 5 to 2 and 1, respectively.

This data set can be obtained online at the following URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=5004;