2009 U.S. Geological Survey (USGS) Topographic LiDAR: Androscoggin County, Maine
This kmz file shows the extent of coverage for the 2009 USGS Androscoggin, ME lidar
USGS Contract Number: G10PC00026 USGS Task Order: G10PD01737 LiDAR was collected at
a 1.0 points per square meter (1.0m GSD) for the county of Androscoggin, Maine while
no snow was on the ground and rivers were at or below normal levels and prior to leaf-on
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
United States Geological Survey, National Geospatial Technical Operations Center (NGTOC)
Documentation links not available.
- DOI/USGS > United States Geological Survey, U.S. Department of the Interior
- DHS/FEMA > Federal Emergency Management Agency, U.S. Department of Homeland Security
- Strategic Alliance for Risk Reduction (STARR)
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||One meter point spacing LiDAR data collection provides the information to create Intensity
Images, Break Lines, Raster DEMs, and fully Classified LiDAR LAS files.
||2009-11-17 to 2009-12-02
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- Remote Sensing
- Digital Elevation Model
- Digital Surface Model
- Androscoggin County
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
| Processing Steps
- Leica software was used in the post processing of the airborne GPS and inertial data
that is critical to the positioning of the sensor during all flights. This software
suite includes Applanix's PosPac and Waypoint's GrafNav solutions. PosPac provides
the smoothed best estimate of trajectory (SBET) that is necessary for Leica's post
processor to develop the point cloud from the LiDAR missions. The point cloud is the
mathematical three dimensional collection of all returns from all laser pulses as
determined from the aerial mission. At this point this data is ready for analysis,
classification, and filtering to generate a bare earth surface model in which the
above ground features are removed from the data set. The point cloud was manipulated
within the Leica software; GeoCue, TerraScan, and TerraModeler software was used for
the automated data classification, manual cleanup, and bare earth generation from
this data. Project specific macros were used to classify the ground and to remove
the side overlap between parallel flight lines. All data was manually reviewed and
any remaining artifacts removed using functionality provided by TerraScan and TerraModeler.
Buffered LAS files were created in GeoCue to provide overedge to the DEM creation.
These tiles were then run through automated scripting within ArcMap and were combined
with the Hydro Flattened Breaklines to create the 2.5 foot DEM. Final DEM tiles were
clipped to the tile boundary to provide a seamless dataset. ERDAS IMG files were then
created as the project deliverable. A manual QA review of the tiles was completed
in ArcMap and Global Mapper to ensure full coverage with no gaps or slivers within
the project area.
- The NOAA Coastal Services Center (CSC) received topographic files in the compressed
LAS.GZ format. The files contained lidar elevation and intensity measurements. The
data were received in Projected Coordinates (Maine State Plane West 1802) 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 uncompressed using
gunzip. 2. The topographic LAS files were converted from Projected coordinates (Maine
State Plane West) to Geographic Coordinates (NAD83). 3. The horizontal units of the
topographic LAS files were converted from feet to decimal degrees. 4. The topographic
LAS files were converted from orthometric (NAVD88) heights to ellipsoidal heights
(NAD83) using Geoid03. 5. The vertical units of the topographic LAS files were converted
from feet to meters. 6. 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: 2013-05-17
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