2004 FEMA Lidar: Portions of Burlington and Camden Counties (NJ)

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.

The LIDAR-derived data were collected in support of shore erosion studies along the shorelines of the Chesapeake Bay. It also supports the Federal Emergency Management Agency's specifications for mapping floodplains. These efforts required detailed elevation data and models, such as those available from LIDAR sensing. The data have also been made available to aid in other projects that require detailed surface, vegetation and/or structure elevations.

10496

These data are part of a suite of spatial data products generated using the LIDAR technology. First and Last returns are generated. From these data, Bare-Earth Mass Points that represent the earths surface are produced. A gridded Digital Elevation Model (DEM) is produced from the Bare Earth Mass Points. Imagery is also created that represents the intensity of the LIDAR return; it is a 1-meter resolution product that resembles a panchromatic Digital Orthophoto Quad (DOQ).

A footprint for the data can be viewed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/5004/supplemental/nj2004_fema_burlington_camden_m5004.kmz

LiDAR point data in LAS 1.2 format

ASPRS classification scheme (1 = unclassified, 2 = ground)

none

Any conclusions drawn from the analysis of this information are not the responsibility of Sanborn, CDM, FEMA, NOAA, the OCM or its partners.

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

None

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. The Department of Natural Resources makes no warranty, expressed or implied, as to the use or appropriateness of Spatial

Data, and there are no warranties of merchantability or fitness for a particular purpose or use. The information contained in Spatial Data

is from publicly available sources, but no representation is made as to the accuracy or completeness of Spatial Data. The Department of

Natural Resources shall not be subject to liability for human error, error due to software conversion, defect, or failure of machines,

or any material used in the connection with the machines, including tapes, disks, CD-ROMs or DVD-ROMs and energy. The Department of Natural

Resources shall not be liable for any lost profits, consequential damages, or claims against the Department of Natural Resources by third

parties. The liability of the Department of Natural Resources for damage regardless of the form of the action shall not exceed any

distribution fees that may have been paid in obtaining Spatial Data.

There are Bare Earth Mass Points files, representing the horizontal coordinates (easting and northing) and vertical position observed and vertical assigned (see process description). Random inspections were made to assure that each line in the file contained these values.

The horizontal coordinate values were designed to meet NSSDA accuracy for data at 1:2400 scale.

Contracted to 18.5 cm RMSE. Data received is listed as QL4, RMSE value of 14.3 cm at the 95% confidence level was determined by an independent accuracy

assessment conducted by Dewberry LLC according to the contract specifications. These specifications followed FEMA Appendix A guidelines regarding assessing vertical accuracy. ; Quantitative Value: 0.143 meters, Test that produced the value:

The RMSE value is 14.3 cm. See the Vertical Positional Accuracy Report section for more

information.

Spatial Systems Associates performed various inspections of the data to ensure: that each file contained the points located within that tile; that tiles were completely filled; that the point density per tile was within expected ranges, and that the tiles were correctly named.

Computational Consulting Services, the LIDAR processing vendor used proprietary algorithms to remove features and artifacts in the First and Last Return data that did not reflect true ground elevation. Subsequent quality assurance testing by Dewberry determined that the data met FEMA and MD DNR specifications for both vertical accuracy and other consistencies with accepted standards. The QA report can be accessed at http://dnrweb.dnr.state.md.us/gis/data/lidar.