2012 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Chehalis River Watershed
This kmz file shows the extent of coverage for the 2012 PSLC Chehalis River Watershed
lidar data set.
Watershed Sciences, Inc. (WSI) collected Light Detection and Ranging (LiDAR) data
for the Chehalis River Watershed study area on January 28th, February 2nd-7th, March
4th-9th, March 21st-23rd, and April 7th, 2012. Acquisition days were not consecutive
due to weather. Data was collected for the Puget Sound LiDAR Consortium in partnership
with the Federal Emergency Management Agency Region X (FEMA), Washington Department
of Natural Resources, and Lewis County. The requested area of 224,713 acres for the
Chehalis River Watershed was expanded to include a 100m buffer to ensure complete
coverage and adequate point densities around survey area boundaries resulting in a
total of 234,556 acres of delivered LiDAR data. The LiDAR survey utilized an Optech
Orion-C and a Leica ALS60 sensor in a Cessna Caravan 208B. Please see "Project Report"
below for specific information regarding the airborne survey and ground survey. This
Lidar survey acheived a nominal point spacing of 10.94 points per square meter.
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
Puget Sound Lidar Consortium (PSLC)
Lidar Dataset Supplemental Information
- Diana Martinez
Puget Sound Lidar Consortium (PSLC)
- DHS/FEMA > Federal Emergency Management Agency, U.S. Department of Homeland Security
- Washington Department of Natural Resources
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||The LAS files can be used to create DEMs and also to extract topographic data in software
that does not support raster data. Other surface features can also be extracted with
custom applications. LiDAR data has a wide range of uses such as earthquake hazard
studies, hydrologic modeling, forestry, coastal engineering, roadway and pipeline
engineering, flood plain mapping, wetland studies, geologic studies and a variety
of analytical and cartographic projects.
||2012-01-28 to 2012-04-07
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- Remote Sensing
- Grays Harbor County
- Lewis County
- Chehalis River Watershed
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
| Processing Steps
- 1. Resolved kinematic corrections for aircraft position data using kinematic aircraft
GPS and static ground GPS data. Software: Waypoint GPS v.8.10, Trimble Business Center
v.2.6 2. Developed a smoothed best estimate of trajectory (SBET) file that blends
post-processed aircraft position with attitude data. Sensor head position and attitude
were calculated throughout the survey. The SBET data were used extensively for laser
point processing. Software: IPAS TC v.3.1 3. Calculated laser point position by associating
SBET position to each laser point return time, scan angle, intensity, etc. Created
raw laser point cloud data for the entire survey in *.las (ASPRS v. 1.2) format. Data
were then converted to orthometric elevations (NAVD88) by applying a Geoid03 correction.
Software: ALS Post Processing Software v.2.74 4. Imported raw laser points into manageable
blocks (less than 500 MB) to perform manual relative accuracy calibration and filter
for pits/birds. Ground points were then classified for individual flight lines (to
be used for relative accuracy testing and calibration). Software: TerraScan v.12.004
5. Using ground classified points per each flight line, the relative accuracy was
tested. Automated line-to-line calibrations were then performed for system attitude
parameters (pitch, roll, heading), mirror flex (scale) and GPS/IMU drift. Calibrations
were performed on ground classified points from paired flight lines. Every flight
line was used for relative accuracy calibration. Software: TerraMatch v.12.001 6.
Resulting data were classified as ground and non-ground points. Statistical absolute
accuracy was assessed via direct comparisons of ground classified points to ground
RTK survey data. Software: TerraScan v.12.004, TerraModeler v.12.002 7. Final version
of data was checked for duplicate points using TerraScan software. No duplicate points
were found. Software: TerraScan v.12.004, TerraModeler v.12.002 8. Bare Earth models
were created as a triangulated surface and exported as ArcInfo ASCII grids at a 3?foot
pixel resolution. Highest Hit models were created for any class at 3-foot grid spacing
and exported as ArcInfo ASCII grids. Hydroflattened Bare Earth models were created
as a triangulated surface with breaklines enforced and exported as ArcInfo ASCII grids
at a 3?foot pixel resolution. Software: TerraScan v.12.004, ArcMap v. 10.0, TerraModeler
- The NOAA Coastal Services Center (CSC) downloaded topographic files in .LAZ format
from PSLC's website. The files contained lidar elevation and intensity measurements.
The data were received in Washington State Plane South Zone 4602, 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 topographic laz files were converted from
orthometric (NAVD88) heights to ellipsoidal heights using Geoid03. 2. The topographic
laz files were converted from a Projected Coordinate System (WA SP South) to a Geographic
Coordinate system (NAD83). 3. The topographic laz files' vertical units were converted
from feet to meters. 4. The topographic laz files' horizontal units were converted
from feet to decimal degrees.
- 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: 2013-06-28
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