2008 USGS South New Jersey County Project Lidar: Portion of Salem County

The South New Jersey County Lidar Project is to provide LiDAR data for the New Jersey Department of Environmental Protection (NJ-DEP)

for Cape May, Cumberland, and part of Salem Counties in New Jersey. These datasets will be the initial acquisition to support

the United States Geological Survey (USGS) and the New Jersey Department of Environmental Protection (NJ-DEP). This LiDAR data set was

collected in April 2008 for the bay side of Salem County and covers 76 square miles. The data are classified as follows:

Class 1 - Unclassified/Extracted Features

Class 2 - Bare Earth, Ground

Class 9 - Water

Class 12 - Overlap

The South New Jersey County Lidar project is to provide LiDAR data for New Jersey Department of Environmental Protection (NJ-DEP).

This project acquired and produced high accuracy bare-earth processed LiDAR data in LAS format and 2.0-meter Digital Elevation

Models (DEMs) in ArcGrid format for approximately 874 square miles covering the 3 New Jersey counties of Cape May, Cumberland, and part

of Salem that is south and west of the Coastal Area Facility Review Act (CAFRA) line.

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A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/543/supplemental/2008_USGS_South_NJ_Lidar_Salem_County.kmz

The following were the data acquisition parameters:

Technical Acquisition Parameters:

Utilizing Leica ALS50 II laser systems which can collect data at laser pulse rates up to 150 KHz, Photo Science flew the project

area at 5,000 feet AGL and utilized a 29 degree full-angle field of view. Flights were accomplished nominally at 115 knots

(ground speed) with a pulse rate of 73,500 Hz (73.5 KHz), collecting four returns per pulse. The scan rate was be set at 42 Hz.

These settings resulted in a swath of 2,586 feet with maximum along track and cross track spacing of 4.62 feet (1.41 meters).

Environmental Acquisition Conditions:

Leaf-Off, snow free, non-flood conditions, low tide.

Low tide: Acquisition was performed within a window of +/- 3 hours from mean low tide for the project area (flight windows that

occur twice a day, that are approximately six hours in length but could be longer depending on the lunar cycle). Low tide is defined

as when the height of tide is different from Mean Lower Low water by fifty percent (50%) of the tide range or less as predicted by the

National Oceanic and Atmospheric Administration (NOAA), National Oceanic Service (NOS) Center for Operational Oceanographic Product

and Services (http://www.co-ops.nos.noaa.gov/). All flight lines affected by tide stage were coordinated with predicted tides at

existing gauges at Cape May, Ship John Shoal, and Reedy Point.

Nominal Pulse density:

Average point density is 1.58 points per sq meter

Average point spacing is 0.8 meters, or 8 decimeters

Calibration procedures:

Photo Science has created a significant boresight facility at the Frankfort, KY airport where the Lidar platforms are stationed

when not in service. Boresighting at this facility takes place with our Lidar sensors at numerous times throughout the year.

Additionally, a mini-calibration site was established at the Millville Municipal Airport at the project site. Additional calibration

flights were conducted over this site to ensure accurate determination of the calibration parameters throughout the times of acquisition.

GPS:

Acquisition for this project was broken into three sub areas with base stations from the NGS database selected near the center of each

acquisition area to serve as control for all lifts. Ground based GPS receivers were occupied at these stations during all aerial collection.

The published NGS positions of these base stations and raw GPS observation data were used in the kinematic GPS post-processing of all

lifts to provide positioning for the point clouds produced for this project.

Maximum and mean differential baseline lengths:

Nominal Maximum base line distance = 20 Miles

Mean base line distance = 11 Miles

Geoid Model Used:

Geoid 03 was used for all elevation conversions to orthometric heights.

Reference System:

Horizontal: New Jersey State Plane Coordinate System, 1983 North American Datum, feet

Elevation in North American Vertical Datum of 1988 (NAVD88), meters

Attributes included: x, y, z to two significant digits; intensity and class as integers. Also includes echo return, time stamp, etc.

LiDAR point data in LAS 1.1; ASPRS classification scheme: Class 1 - Unclassified/Extracted Features; Class 2 - Bare Earth Ground;

Class 9 - water; Class 12 - overlap.

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or

its partners.

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

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 following aspects of the LiDAR data was verified during the course of the project processing:

-Data accuracy and errors

-Anomaly checks through full-feature hillshades and 3-D modeling

-Post automated classification Bare-earth verification

-Final quality control of deliverable products ensuring integrity, graphical quality

Compiled to meet 1 m horizontal accuracy

Independent accuracy testing was performed by Dewberry using 60 high accuracy quality control checkpoints distributed around Salem,

Cumberland, and Cape May County on near level open bare terrain, urban terrain and near level vegetated terrain. Dewberry uses testing

procedures consistent with those specified in the National Standard for Spatial Data Accuracy (NSSDA). Target equivalent to

2 ft contours: 0.363 m

FVA - Fundamental Vertical Accuracy in open terrain (RMSEz x 1.9600): 0.13 m;

CVA - Consolidated Vertical Accuracy (95th Percentile) all categories: 0.16 m;

SVA - Supplemental Vertical Accuracy (95th Percentile) in mixed vegetation: 0.18 m;

SVA - Supplemental Vertical Accuracy (95th Percentile) in urban: 0.12 m;

13 points are included inside the Salem dataset, the consolidated accuracy (95th Percentile all categories) for these points is 0.12 m.

; Quantitative Value: 0.13 meters, Test that produced the value:

National Standard for Spatial Data Accuracy.

Using NSSDA standards, this LiDAR dataset was tested 0.13 m fundamental vertical accuracy at 95% confidence level in open terrain

using RMSEz x 1.9600, compared to 0.363 m for 2 ft equivalent contour.

Data completeness and integrity was verified.

All LAS formatted LiDAR data are validated to ensure that data on delivery media is in correct physical format and is readable and correctly

georeferenced and projected. Note that LiDAR intensity is not calibrated or normalized.