2006 U.S. Geological Survey (USGS) Bare Earth Topographic LiDAR: North Puget Sound, Washington

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%

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 modeling.

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The third-party QA report for this data set may be accessed at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/1451/supplemental/2006_NorthPugetSound_lidar_Task_Order.pdf

A footprint of this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/1451/supplemental/2006_NorthPugetSound_lidar_geo_footprint.kmz

LiDAR points in LAS 1.1 format

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Any conclusions drawn from the analysis of this information are not the responsibility

of Photo Science, NOAA, GADNR, the Office for Coastal Management or its partners.

This data can be obtained on-line at the following URL:

https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=1451

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Users should be aware that temporal changes may have occurred since this data set was collected

and some parts of this data may no longer represent actual surface conditions. Users should not use

this data for critical applications without a full awareness of its limitations. These data

depict the heights at the time of the survey and are only accurate for that time.

The USGS task order required a a vertical bare earth accuracy of 18.5cm @ 95% confidence, a 1m horizontal RMS @ 95% confidence, and

no data voids due to system malfunctions of lack of overlap. The project did not meet the specifications for vertical accuracy or

data voids.

The LiDAR data was compiled to meet a 1 meter horizontal accuracy. The calibration of

the LiDAR sensor itself and the calibration process of the data produced by this sensor ensure

that this accuracy is met.

; Quantitative Value: 1 meters, Test that produced the value: Value stated as RMSE @ 95% confidence in meters

The LiDAR data was tested by Sanborn for vertical accuracy. Sanborn collected

a total of 60 ground control points for use in verifying the vertical accuracy of the classified LiDAR data in North Puget Sound.

Only 45 ground control points proved valid. These points were tested against the classified LiDAR data.

; Quantitative Value: 0.55 meters, Test that produced the value: RMSEz in meters

Datasets contain complete coverage of tiles except where previously discussed.

Deliverables were tested by Sanborn for vertical accuracy and consistency. There are two small unsurveyed areas near the North Fork Nooksack River.

There are three areas of sparse returns located along Finney Creek south of Concrete, near Marblemount and along the Skagit River near Ross Dam.