2011 U.S. Geological Survey (USGS) Alabama Topographic LiDAR: Baldwin County East
This kmz file shows the extent of coverage for the 2011 USGS Balwin County, AL lidar
USGS Contract: G10PC00026 Task Order Number: G10PD02126 LiDAR was collected at a 2.0
meter nominal post spacing (2.0m GSD) for approximately 329 square miles of Baldwin
County, Alabama, while no snow was on the ground and rivers were at or below normal
levels. Project was divided into two separate AOIs, Baldwin West and Baldwin East.
Project meets U.S. Geological Survey National Geospatial Program Base LiDAR Specification,
Version 13. LAS Classifications: Class 1: Unclassified Class 2: Bare Earth Ground
Class 5: High Vegetation Class 7: Noise (Low points) Class 9: Water Class 10: Ignored
Ground (within 1m of breakline) Class 12: Overlap Class 13: Witheld
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
Documentation links not available.
- DOI/USGS > United States Geological Survey, U.S. Department of Interior
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||Classified LAS files are used to show the manually reviewed bare earth surface. This
allows the user to create Intensity Images, Break Lines and Raster DEMs.
||2011-01-22 to 2011-01-28
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- remote sensing
- Baldwin County
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
| Processing Steps
- Applanix software was used in the post processing of the airborne GPS and inertial
data that is critical to the positioning and orientation of the sensor during all
flights. POSPac MMS provides the smoothed best estimate of trajectory (SBET) that
is necessary for Optech'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 Optech 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. The Baldwin County project (G10PD02126) is immediately
adjacent to the NGOM Mobile Bay LiDAR project (G10PD00578). A manual review was performed
to ensure that the two datasets tied together as seemlessly as possible. Revisions
were made to both the LAS and breakline datasets as needed in order to achieve a smooth
transition between the two datasets. NGOM Mobile Bay data was used to produce full
tile deliverables on the eastern edge of the Baldwin County West dataset and the western
edge of the Baldwin County East dataset. Upon completion of the Baldwin County deliverables,
revised copies of the NGOM deliverables that border the Baldwin dataset will be provided
in order to ensure that the two datasets agree with each other. All Class 2 LiDAR
data inside of the collected breaklines were then classified to Class 9 using TerraScan
macro functionality. A buffer of 1 meter was also used around each hydro flattened
feature. The breakline files were then translated to ESRI Shapefile format using ESRI
conversion tools. Data was then run through additional macros to ensure deliverable
classification levels matching LAS ASPRS Classification structure. GeoCue functionality
was then used to ensure correct LAS Version. In house software was used as a final
QA/QC check to provide LAS Analysis of the delivered tiles.
- The NOAA Coastal Services Center (CSC) received topographic files in LAS format. The
files contained lidar elevation and intensity measurements. The data were received
in UTM Zone 16 (NAD83) coordinates and were vertically referenced to NAVD88 using
the Geoid09 model. The vertical units of the data were meters. CSC performed the following
processing for data storage and Digital Coast provisioning purposes: 1. The topographic
las files were converted from orthometric (NAVD88) heights to ellipsoidal heights
using Geoid09. 2. The topographic las files were horizontally converted from UTM coordinates
(m) to NAD83 Geographic coordinates (dd). 3. ASPRS Class 11 (Witheld) was changed
to Class 13 (Witheld). 4. 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: 2013-03-28
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