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Metadata Identifier: gov.noaa.csc.maps:ct2006_fema_coastal_m1468
MD_DataIdentification
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2006 Federal Emergency Management Agency (FEMA) Topographic LiDAR: Coastal
Connecticut
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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. The LiDAR flightlines for this project
was planned for a 50% acquisition overlap. The nominal resolution of this project
without overlap is 1.25m. 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 v1.0 format,
classified according to ASPRS Class Code 2=Ground 1=Undefined. Water is included in
the bare earth ground model, except where the entire tile is covered by water. The
following regions of Connecticut are included in this project: Fairfield County -
130 square kilometers New Haven - 170 square kilometers Middlesex - 29 square kilometers
New London - 157 square kilometers Please note that the LiDAR intensity is not calibrated
or normalized. The intensity value is meant to provide relative signal return strengths
for features imaged by the sensor.
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SV_Identification
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2006 Federal Emergency Management Agency (FEMA) Topographic LiDAR: Coastal Connecticut |
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None |
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North American Datum 1983 |
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resourceProvider |
http://www.epsg-registry.org/export.htm?gml=urn:ogc:def:crs:EPSG::4269 |
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Claude Vickers |
Terrapoint USA |
Production Manager |
claude.vickers@terrapoint.com |
processor |
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DHS/FEMA > Federal Emergency Management Agency, U.S. Department of Homeland Security |
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originator |
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NOAA CSC (originator) |
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DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic
and Atmospheric Administration, U.S. Department of Commerce
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csc.info@noaa.gov |
originator |
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NOAA CSC (publisher) |
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DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic
and Atmospheric Administration, U.S. Department of Commerce
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csc.info@noaa.gov |
publisher |
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NOAA CSC(distributor) |
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DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic
and Atmospheric Administration, U.S. Department of Commerce
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csc.info@noaa.gov |
distributor |
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NOAA CSC (processor) |
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DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic
and Atmospheric Administration, U.S. Department of Commerce
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csc.info@noaa.gov |
processor |
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EPSG Registry |
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European Petroleum Survey Group |
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publisher |
http://www.epsg-registry.org/ |
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Mike Sutherland(author) |
Mike Sutherland |
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
of Commerce
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mike.sutherland@noaa.gov |
author |
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Mike Sutherland |
Mike Sutherland |
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
of Commerce
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mike.sutherland@noaa.gov |
distributor |
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Mike Sutherland (processor) |
Mike Sutherland |
DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department
of Commerce
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mike.sutherland@noaa.gov |
processor |
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National Oceanic and Atmospheric Administration (NOAA) |
Coastal Services Center |
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pointOfContact |
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Shiva Shenoy |
Terrapoint USA |
Production Manager |
shiva.shenoy@terrapoint.com |
processor |
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http://www.epsg-registry.org/ |
European Petroleum Survey Group Geodetic Parameter Registry |
Registry that accesses the EPSG Geodetic Parameter Dataset, which is a structured
dataset of Coordinate Reference Systems and Coordinate Transformations.
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search |
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http://www.epsg-registry.org/export.htm?gml=urn:ogc:def:crs:EPSG::4269 |
NAD83 |
Link to Geographic Markup Language (GML) description of reference system. |
information |
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Ellipsoid in Meters |
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urn:ogc:def:crs:EPSG::4269 |
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Bounding Box |
Temporal Extent |
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-73.659952 |
-71.829101 |
41.540542 |
40.979296 |
2006-12-16 |
2006-12-18 |
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-73.659952 |
-71.829101 |
41.540542 |
40.979296 |
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Lidar Use Limitation |
These data depict the elevations at the time of the survey and are only
accurate for that time. 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. Any conclusions
drawn from analysis of this information are not the responsibility of NOAA
or any of its partners. These data are NOT to be used for navigational purposes.
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Ellipsoid |
Ellipsoid in Meters |
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NAD83 |
urn:ogc:def:crs:EPSG::4269 |
North American Datum 1983 |
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2007-01-01T00:00:00 |
- 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 4.5. Distances from base station to aircraft were kept to a maximum of 35 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 5cm average but no larger than 12 cm
being recorded. - Calculation of 3D laser points (raw data) The post-processing software
to derive X, Y, Z values from roll, pitch, yaw, and range is Optech's Realm. - Classification
and Editing The data was processed using the software TerraScan, and following the
methodology described herein. The initial step is the setup of the TerraScan project,
which is done by importing client provided tile boundary index encompassing the entire
project areas. The 3D laser point clouds, in binary format, were imported into the
TerraScan project and divided in 1407 tiles, as per the contract specifications. 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 is 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. - Projection Transformation The data was processed in the native
UTM zone in meters and then transformed to the Connecticut State Plane final projection
system and US survey feet using an in-house transformation software which uses the
Coorpscon DLL.
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2007-12-01T00:00:00 |
- General Overview The Airborne LiDAR survey was conducted using an
OPTECH 3100EA flying at a nominal height of 1550 metres AGL with a total angular coverage
of 40 degrees. Flight line spacing was nominally 564 metres providing overlap of 50%
on adjacent flight lines. Lines were flown in east/west and north/south orientated
blocks to best optimize flying time considering the layout for the project. - Aircraft
A Piper Navajo, registration C-FQQB was used for the survey. This aircraft has a flight
range of approximately 6.5 hours and was flown at an average altitude of 1550, thereby
encountering flying altitudes of approximately 1550 metres above sea level (ASL).
The aircraft was staged from the East Haven CT Airport, and ferried daily to the project
site for flight operations. - GPS Receivers A combination of Sokkia GSR 2600 and NovAtel
DL-4+ 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 For both Connecticut and Rhode Island Coastline Sites; a total of 6 missions
were flown for this project with flight times ranging approximately 31 hours under
good meteorological and GPS conditions. 72 flight lines were flown over the Connecticut
Coastline site to provide complete coverage.
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2013-04-01T00:00:00 |
The NOAA Coastal Services Center (CSC) received the topographic files
in LAZ V1.0 format. The files contained lidar elevation measurements. The data were
received in Connecticut State Plane coordinates, NAD83 (Zone 0600) and were vertically
referenced to NAVD88 using the Geoid03 model. The vertical units of the data were
feet. CSC performed the following processing for data storage and Digital Coast provisioning
purposes: 1. The topographic las files were converted from a Projected Coordinate
System (Connecticut SP 0600) to a Geographic Coordinate system (NAD83). 2. The topographic
las files' horizontal units were converted from US survey feet to decimal degrees.
3. The topographic las files were converted from orthometric (NAVD88) heights to ellipsoidal
heights using Geoid03. 4. The topographic las files' vertical units were converted
from survey feet to meters. 5. The data were converted to LAZ format.
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2013-04-25T00:00:00 |
The NOAA National Geophysical Data Center (NGDC) received lidar data
files via ftp transfer from the NOAA Coastal Services Center. The data are currently
being served via NOAA CSC Digital Coast at http://www.csc.noaa.gov/digitalcoast/.
The data can be used to re-populate the system. The data are archived in LAS or LAZ
format. The LAS format is an industry standard for LiDAR
data developed by the American Society of Photogrammetry and Remote Sensing (ASPRS);
LAZ is a loseless compressed version of LAS developed by
Martin Isenburg (http://www.laszip.org/). The data are exclusively in geographic coordinates
(either NAD83 or ITRF94). The data are referenced vertically to
the ellipsoid (either GRS80 or ITRF94), allowing for the ability to apply the most
up to date geoid model when transforming to orthometric heights.
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