2009 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Douglas Co.
This kmz file shows the extent of coverage for the 2009 PSLC Douglas County, WA lidar
Watershed Sciences, Inc. (WS) collected Light Detection and Ranging (LiDAR) data of
the Douglas County PUD area of interest (AOI) east of Wenatchee, WA on May 2nd ? May
27th, 2009. The total area of delivered LiDAR is 105,134 acres (Figure 1). The requested
area was expanded to include a 100 m buffer to ensure complete coverage and adequate
point densities around survey area boundaries.
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)
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||Provide high resolution terrain elevation and land cover elevation data.
||2009-05-02T1200 to 2009-05-27T1200
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- Remote Sensing
- Douglas County
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
| Processing Steps
- Acquisition. The LiDAR survey uses a Leica ALS50 Phase II laser system. For the Douglas
County survey area, the sensor scan angle was +/- 14 degrees from nadir with a pulse
rate designed to yield an average native density (number of pulses emitted by the
laser system) of = 8 points per square meter over terrestrial surfaces. All survey
areas were surveyed with an opposing flight line side-lap of more than 50% (more than
100% overlap) to reduce laser shadowing and increase surface laser painting. The Leica
ALS50 Phase II system allows up to four range measurements (returns) per pulse, and
all discernable laser returns were processed for the output dataset. It is not uncommon
for some types of surfaces (e.g. dense vegetation or water) to return fewer pulses
than the laser originally emitted. These discrepancies between ?native? and ?delivered?
density will vary depending on terrain, land cover and the prevalence of water bodies.
- Resolved kinematic corrections for aircraft position data using kinematic aircraft
GPS and static ground GPS data. Software - Waypoint GPS v.8.10, Trimble Geomatics
Office v.1.62 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 v.1.4 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 v1.1) format. Software
- ALS Post Processing Software v.2.69 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.9.001
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.9.001 Position and attitude
data were imported. Resulting data were classified as ground and nonground points.
Statistical absolute accuracy was assessed via direct comparisons of ground classified
points to ground RTK survey data. Data were then converted to orthometric elevations
(NAVD88) by applying a Geoid03 correction. Ground models were created as a triangulated
surface and exported as ArcInfo ASCII grids at a 3-foot pixel resolution. Software
- TerraScan v.9.001, ArcMap v.9.3, TerraModeler v.9.001
- The NOAA Coastal Services Center (CSC) downloaded topographic files in LAZ format
from PSLC's website. The files contained lidar easting, northing, elevation, intensity,
return number, class, scan angle and GPS time measurements; the data was received
in state plane Washington (in feet) and vertical coordinates were referenced to NAVD88
in feet using the Geoid03 model. CSC performed the following processing for data storage
and Digital Coast provisioning purposes: 1. The All-Return LAZ files were checked
for bad elevations 2. The laz files were converted from a Projected Coordinate System
(SP 4601) to a Geographic Coordinate system (NAD83) 3. The laz files were then converted
to ellipsoidal vertical units in meters using the geoid03 conversion.
- 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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