2001-2002 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Island County and
Northeast Jefferson County, Washington
This kmz file shows the extent of coverage for the 2001 PSLC Island and NE Jefferson
Counties, WA lidar data set.
TerraPoint surveyed and created this data for the Puget Sound LiDAR Consortium under
contract. The area surveyed is approximately 525 square miles and covers all of Island
County, WA and the Northeast portion of Jefferson County, WA. All data was collected
during ideal conditions (leaf-off). The LAS files were derived from all returns ASCII
files contain the X,Y,Z values of all the LiDAR returns collected during the survey
mission. The GPS time, scan angle and return numbers of each point were preserved
in the conversion from ASCII to LAS. The LAS files were classified into the following
ASPRS classes: (1) Unclassified (2) Bare Earth. Ground and water points are included
in Class 2 (Bare Earth). Futher details are available in the Process Steps below.
No ancillary data, such as intensity, is available for this data. Initially this dataset
was flown in 2001 with a 30% overlap between flight lines which did not meet specifications.
The dataset was reflown in 2002 with a 50% overlap between flight lines as the rest
of the PSLC data. The data is broken down into USGS quarter quads and then into 25
tiles within each quarter quad. Due to the overlap the nominal point spacing of the
dataset is 1.0 meter.
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 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. This high accuracy data can be used at scales up to 1:12000 (1
inch = 1,000 feet). 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.
||2001-01-09 to 2002-03-23
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- Remote Sensing
- Puget Sound
- Puget Lowland
- Island County
- Jefferson County
- Whidbey Island
- Camano Island
- Port Townsend
| 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
- ASCII file generation All Point returns with all their attributes were directly exported
into ASCII files. These were first divided into USGS quarter quads (3.25 minute by
3.25 minute) and then in 25 tiles per quarter quad.
- The NOAA Coastal Services Center (CSC) received topographic files in ASCII .TXT format.
The files contained lidar elevation measurements. 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 ASCII .TXT files were converted to LAS version 1.2 using LAStools' txt2las tool.
2. Bare earth points were classified using LAStools' lasground tool. 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 (GCS). 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 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: 2013-04-25
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