2006 Federal Emergency Management Agency (FEMA) Topographic Lidar: Bristol and Plymouth
This kmz file shows the extent of coverage for the 2006 FEMA Bristol and Plymouth
counties, MA lidar data set.
FEMA Contract No. EME-2003-CO-0340 FEMA Task Order T018 Sanborn Map Company furnished
the collection and processing, and development of Lidar and contours using photogrammetry
to support the FEMA mapping requirements for a total of 142 square miles in coastal
areas in Plymouth and Bristol Counties in Massachusetts. The 142 square miles includes
the communities of Westport, Dartmouth, New Bedford, Fairhaven, Mattapoisett, Marion,
and Wareham. The project area was defined using a buffered shapefile with limits along
the coastline. The project area included a portion of both counties. All lidar data
was acquired during November 2006 by Sanborn. Orthophotography used to create 2D breaklines
was produced in 2005 by MassGIS as part of its statewide orthophoto program. All lidar
data that was acquired was produced in accordance with FEMA specifications (Source:
FEMA Guidelines and Specifications, Appendix N, Section N.1.2). Lidar Acquisition
Parametes: Average Altitude: 1,200 Meters AGL Airspeed: ~120 Knots Scan Frequency:
36 Hertz Scan Width Half Angle: 16 Degrees Pulse Rate: 50000 Hertz The data being
distributed through the NOAA Digital Coast are Gridded Bare-Earth LAS files.
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
||Federal Emergency Management Agency, Region I
- Massachusetts Office of Geographic Information (MASSGIS)
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||The LIDAR derived data sets, including the first and last returns, a Gridded DEM,
TIN file, 2' contours in ESRI geodatbase format and masspoint and Breakline files
were developed to support Camp Dresser and McKee's continued development of updated
Digital Flood Insurance Rate Maps and flood insurance studies for coastal areas in
Massachusetts. Contours are based on bare earth LIDAR and breaklines digitized from
2D orthophotography (subsequently draped over the 3D LIDAR points) (Source: FEMA Guidelines
and Specs, Appendix N). Coastal shoreline areas were set a 0.00 elevation to cartographically
||2006-11-10 to 2006-11-26
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- Land Surface
- Digital Terrain Model
- Elevation Data
- Flow vectors
- Bristol County
- Plymouth County
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
| Processing Steps
- Using an Optech 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
2.0 square meters per sample * Swath width 728 meters * Flight altitude 1000 meters
* flight line spacing -589 meters with 125 meters overlap *Scan Frequency- 35 Hz *Scan
Angle- 20 degrees * Aircraft ground speed -- 140 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. The bare earth
elevation data was draped over the existing orthophotos. Breaklines for hydrographic
features, bridges, culverts and major roadways were captured in 2D. Elevations were
associated to the breaklines by draping onto the Lidar data. The DTM was then used
to produce a TIN. The TIN was used to generate 2-ft contours.
- The NOAA Coastal Services Center (CSC) received topographic files in ASCII format.
The files contained lidar elevation measurements. The data were received in Massachusetts
State Plane Mainland (Zone 2001), NAD83 coordinates 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 ASCII files were converted to LAS V1.2 using LASTools' txt2las. 2. The topographic
las file '8002645' was found to be corrupt and removed from the data set. 3. All points
in the topographic las files were converted to Class 2 (Ground) using LASTools' las2las.
4. The topographic las files were found to contain noise, those points were manually
reclassified to Class 7 (Noise) using Merrick MARS7. 5. All additional VLRs in the
topographic las files' header used by MARS7 were removed using LASTools' las2las.
6. The topographic las files were converted from orthometric (NAVD88) heights to ellipsoidal
heights using Geoid03. 7. The topographic las files were converted from a Projected
Coordinate System (MA SP 2001) to a Geographic Coordinate System (NAD83). 8. The topographic
las files' horizontal units were converted from feet to decimal degrees. 9. The topographic
las files' vertical units were converted from feet to meters. 10. The data were converted
to LAZ format.
- 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
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
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
the ellipsoid (either GRS80 or ITRF94), allowing for the ability to apply the most
up to date geoid model when transforming to orthometric heights.
Metadata Last Modified: 2013-12-06
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