2006 U.S. Geological Survey (USGS) Bare Earth Topographic LiDAR: North Puget Sound,
This kmz file shows the extent of coverage for the 2006 USGS North Puget Sound lidar
USGS Contract Number: 01CRCN0014 In Spring, 2006 Sanborn was contracted by the USGS
to survey aprocimately 1,735 square miles of western Whatcom and Skagit Counties in
Washington state. All data was collected during ideal conditions (rivers at or below
mean level, leaf off, etc.). For this collect two sensors were used: The Leica ALS-50
(High Relief Collection) and Optech 2050 (High and Low Relief Collection). LiDAR calibrations
were performed to determine and therefore eliminate systematic biases that occur between
the the two sensors. Once the biases were determined they were modeled out. The Leica
ALS-50 produced an average point spacing of 1.4 meters. The Optech 2050 produced an
average point spacing of 1.3 meters. All points are classified as Class 2 (Ground)
which includes water points and any possibly remaining artifacts. Leica ALS-50 LiDAR
Acquisition Paramters: Avg. Altitude: 1,500 meters AGL Airspeed: ~120 Knots Scan Freq:
36 Hertz Scan Width Half Angle: 36 Degrees Pulse Rate: 60,000 Hertz Overlap: 44-60%
Optech 2050 LiDAR Acquisition Parameters: Avg. Altitude: 1,200 meters AGL Airspeed:
~120 Knots Scan Freq: 30 Hertz Scan Width Half Angle: 40 Degrees Pulse Rate: 50,000
Hertz Overlap: 30-50%
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
United States Geological Survey, National Geospatial Technical Operations Center (NGTOC)
Documentation links not available.
- DOI/USGS > United States Geological Survey, U.S. Department of the Interior
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||This LiDAR operation was designed to provide a highly detailed ground surface dataset
to be used for the development of topographic mapping, contour mapping and hydraulic
||2006-05-05 to 2006-09-03
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- Remote Sensing
- North Puget Sound
- Whatcom County
- Skagit County
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
| Processing Steps
- Final post-processing of LiDAR data involves several steps. The airborne GPS data
was post-processed using Waypoint's GravNAVTM software (version 7.5). A fixed-bias
carrier phase solution was computed in both the forward and reverse chronological
directions. The data was processed for both base stations and combined. In the event
that the solution worsened as a result of the combination of both solutions the best
of both solutions was used to yield more accurate data. The GPS trajectory was combined
with the raw IMU data and post-processed using Applanix Inc.'s POSPROC (version 4.3)
Kalman Filtering software. This results in a two-fold improvement in the attitude
accuracies over the real-time INS data. The best estimated trajectory (BET) and refined
attitude data are then reintroduced into the LEICA ALS post processor or REALM Survey
Suite OPTECH to compute the laser point-positions. The trajectory is then combined
with the attitude data and laser range measurements to produce the 3-dimensional coordinates
of the mass points. All return values are produced within ALS Post Processing software
or REALM Survey Suite OPTECH software. The multi-return information minus the last
return provides a useful depiction of the "canopy" within the project area. The last
return is further processed to obtain the "Bare Earth Dataset" as a deliverable. All
LiDAR data is processed using the binary LAS format 1.0 file format. LiDAR filtering
was accomplished using TerraSolid, TerraScan LiDAR processing and modeling software.
The filtering process reclassifies all the data into classes within the LAS formatted
file based scheme set using the LAS format 1.0 specifications or by the client. Once
the data is classified, the entire data set is reviewed and manually edited for anomalies
that are outside the required guidelines of the product specification or contract
guidelines, whichever apply. The coordinate and datum transformations were then applied
to the data set to reflect the required deliverable projection, coordinate and datum
systems as provided in the contract. The final data is in State Plane Washington North
Coordinate System with the horizontal and vertical units being in feet.
- The NOAA Coastal Services Center (CSC) received topographic file in ASCII .XYZ 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 .XYZ files were converted to LAS version 1.1 using Global Mapper. 2. All
points in Class 0 (Never Classified) were changed to Class 2 (Ground). This includes
water points. 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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