2004 Puget Sound Lidar Consortium (PSLC) Topographic Bare-Earth Lidar: Pierce County,
This kmz file shows the extent of coverage for the 2004 PSLC Pierce County, WA lidar
Terrapoint surveyed and created this data for the Puget Sound LiDAR Consortium under
contract. The project area covers approximately 814 square miles of western Pierce
County. A majority of the data was collected between January 21st and March 08, 2004.
Two small areas were reflown during spring 2005.
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
Puget Sound Lidar Consortium (PSLC)
Documentation links not available.
- Diana Martinez
Puget Sound Lidar Consortium (PSLC)
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||The LiDAR bare earth ASCII files can be used to create DEM and also to extract topographic
data in software that does not support raster data. This high accuracy data can be
used at scales up to 1:12000 (1 inch = 1,000 feet). The LiDAR bare earth 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.
||2004-01-24 to 2004-03-08
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- Remote Sensing
- Bare Earth
- ground surface
- Pierce County
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
| Processing Steps
- Acquisition. Lidar data were collected in leaf-off conditions (approximately 1 November
- 1 April) from a fixed-wing aircraft flying at a nominal height of 1,000 meters above
ground surface. Aircraft position was monitored by differential GPS, using a ground
station tied into the local geodetic framework. Aircraft orientation was monitored
by an inertial measurement unit. Scan angle and distance to target were measured with
a scanning laser rangefinder. Scanning was via a rotating 12-facet pyramidal mirror;
the laser was pulsed at 30+ KHz, and for most missions the laser was defocussed to
illuminate a 0.9m-diameter spot on the ground. The rangefinder recorded up to 4 returns
per pulse. Flying height and airspeed were chosen to result in on-ground pulse spacing
of about 1.5 m in the along-swath and across-swath directions. Most areas were covered
by two swaths, resulting in a nominal pulse density of about 1 per square meter.
- Processing. GPS, IMU, and rangefinder data were processed to obtain XYZ coordinates
of surveyed points. For data acquired after January, 2003 (NW Snohomish, Mt Rainier,
Darrington, and central Pierce projects), survey data from areas of swath overlap
were analysed to obtain best-fit in-situ calibration parameters that minimize misfit
between overlapping swaths. This reduces vertical inconsistency between overlappoing
swaths by about one-half. Heights were translated from ellipsoidal to orthometric
(NAVD88) datums via GEOID99
- Post-processing. Return points were then classified semi-automatically as ground (and
water), not-ground (vegetation and structures) and blunder. For 2000 and 2001 data,
the despike virtual deforestation algorithm described by Haugerud and Harding (2001)
was used. After 2001, TerraPoint shifted to Terrascan software, which includes additional
classification algorithms, allows for greater intervention by a human operator, and
generally produces better bare-earth surface models.
- ASCII file generation The X,Y,Z values of the ground returns were exported into ASCII
files. These were divided into USGS quarter quads (3.25 minute by 3.25 minute).
- Breakng down ASCII files TerraPoint shipped data in USGS quarter-quads (3.25 minute
by 3.25 minute). To reduce the file size and make them more user friendly, each quarter
quad files was further broken down into 25 smaller tiles.
- The NOAA Coastal Services Center (CSC) received topographic files in ASCII .txt format.
The files contained lidar elevation measurements only. The data were received in Washington
State Plane North Zone 4601, NAD83 coordinates and were vertically referenced to NAVD88
using the Geoid99 model. The vertical units of the data were feet. CSC performed the
following processing for data storage and Digital Coast provisioning purposes: 1.
The parsed ASCII .txt files were converted to LAS version 1.2 using LAStools' txt2las
tool. 2. The topographic las files' classifications off all points were changed from
Class 0 (Never Classified) to Class 2 (Ground). 3. The topographic las files were
converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid99.
4. The topographic las files were converted from a Projected Coordinate System (WA
SP North) to a Geographic Coordinate system (NAD 83). 5. The topographic las files'
vertical units were converted from feet to meters. 6. The topographic las files' horizontal
units were converted from feet to decimal degrees. 7. The data were converted to LAZ
- 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: 2013-10-17
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