2005 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: North Puget Sound Lowlands

Terrapoint collected Light Detection and Ranging (LiDAR) data contributing to the Puget Sound Lowlands project of 2005. Arlington, City of Snohomish, Snohomish Floodplains, Lummi-Nooksack, Nooksack North Fork, Marysville, Port Susan and Fisher Slough, Skagit Environmental Bank, Cavanaugh, Sauk South, Sauk South, Sauk-Suiattle, Skagit Bacon, Edmonds, Mt. Lake Terrace and Mukilteo of Central and North Central Washington. This data set covers approximately 5,285 square miles.

The Airborne LiDAR survey was conducted using Terrapoint's 40 kHz ALTMS (Airborne Laser Terrain Mapping System), flying at an optimum height of 3500 ft AGL at 140 knots. The system consists of a 36-degree full angle laser, a Trimble 4700 GPS receiver and a Honeywell H764 IMU unit. This metadata is a collaboration of metadata reports from each of the individual 15 projects. The Puget Sound Lowlands project covers more areas over 2000-2004, these areas were excluded for this project.

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. 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.

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

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/2579/supplemental/wa2005_pslc_northpugetlowlands.KMZ

Reports explaining collection and quality assurance is available at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/2579/supplemental/wa2005_pslc_northpugetlowlands.pdf

A PSLC shapefile containing the individual projects which were combined for this project is available at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/2579/supplemental/wa2005_pslc_northpugetlowlands.zip

Individual report collaborations:

project, area (sq mi), date(s) collected, vert. acc (cm), horiz acc. (cm), RMSE (m) - Arlington 10, 2/23/2005-2/26/2005, 25, 60, 0.063 - City of Snohomish, 6, 2/26/2005, 25, 60, 0.075 - Snohomish Floodplains, 118, 2/23/2005-2/26/2005, 0.064 - Lummi-Nooksack, 3,4/20/2005, 25, 60, 0.053 - Nooksack North Fork, 21.5, 3/23/2005, 25, 60, 0.031 - Marysville, 34, 5/15/2005-6/15/2005, 25, 60, 0.063 - Port Susan (PS) and Fisher Slough (FS), 41 (FS 18.5) (PS 22.5), 3/15/2005-4/15/2005, 25, 60, FS 0.076 + PS 0.086 - Skagit Environmental Bank, 1.26, 4/6/2005, 25, 60, 0.092 - Cavanaugh, 62, 4/6/2005-4/10/2005, 25, 60, 0.046 - Sauk North, 42, 4/10/2005-4/19/2005, 25, 60, 0.055 - Sauk South, report not available - Sauk-Suiattle, 8, 4/10/2005-4/19/2005, 25, 60, 0.055 - Skagit Bacon, 13, 4/8/2005-4/10/2005, 25, 60, 0.057 - Edmonds, 11, 2/27/2005, 25, 60, 0.100 - Mt. Lake Terrace, 4, 7/15/2005-9/15/2005, 25, 60, 0.100 - Mukilteo, 16, 2/27/2005, 25, 60, 0.100

LiDAR points in LAZ format (ASPRS Classes 1,2,7)

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

of Terrapoint, PSLC, NOAA, 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=2579

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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.

Elevations are recorded in floating-point meters and the vertical datum is ellipsoidal (GEOID03). There are no other attribute tables.

Horizontal positional accuracy for LiDAR is dependent upon

the quality of the GPS/INS solution, sensor calibration and ground conditions at the time of

data capture. The standard system results for horizontal accuracy are less than 1 meter.

; Quantitative Value: 0.60 meters, Test that produced the value:

Reporting highest reported values with uncertainty of likelihood of less than 0.60 m horizontal accuracy

values. 20 - 60 centimeters on all but extremely hilly terrain.

Laser point returns were optimized for internal consistency based on independent data from the LiDAR system, IMU, and aircraft. Noise points (e.g. pits and birds) were filtered from the data based on known elevation ranges. This data was then compared to 10,000+ real time kinematic ground survey points collected to verify the vertical and horizontal accuracies of the data set.; Quantitative Value: 0.25 meters, Test that produced the value: Averaged to 25 cm. 10-15 centimeters on Hard Surfaces (roads and buildings), 15-25 centimeters on Soft/Vegetated Surfaces (flat to rolling terrain), 25-40 centimeters on Soft/Vegetated Surfaces (hilly terrain)

LiDAR data has been collected and processed for all areas within the project study area.

LiDAR flight lines have been examined to ensure that there was at least 50% sidelap, there are no gaps between flightlines, and overlapping flightlines have consistent elevation values.

Shaded relief images have been visually inspected for data errors such as pits, border artifacts, gaps, and shifting. The data was examined at a 1:3500 scale.