Data Management Plan

This dataset is a LiDAR (Light Detection and Ranging) point cloud of the coastal tidal parts of Skagit and Snohomish Counties in WA State. The National Oceanic and Atmospheric Administration’s Office for Coastal Management contracted with Tetra Tech to acquire and process airborne LiDAR over an area of about 186 square miles. Data was to be acquired within a 2 hour window of low tide. Deliverables included classified LiDAR point clouds, breaklines and digital elevation models (DEM). LiDAR data was acquired on 13 and 14 of August 2019. The coastal area was covered in one flight on 8/14 while the inland area was covered on 8/13. The coastal flight took place on 8/14 with a tide window between -0.7 and +0.5 foot. For the airborne LiDAR flight Tetra Tech subcontracted with Eagle Mapping. The data was acquired with a Riegl LMS VQ780i sensor. A ground control survey was conducted to collect calibration points and check points. For the ground survey, Tetra Tech contracted with Compass Data. The LiDAR data and derivative products were to be based on the USGS LiDAR Base Specifications. The coordinate reference system is UTM Zone 10N meters, NAD83(2011). The vertical datum is NAVD88 with Geoid12B.

Process Steps:

• 2019-08-14 00:00:00 - Flight Acquisition: LiDAR data was acquired on 13 and 14 of August 2019. The coastal area was covered in one flight on August 14 while the inland area was covered on August 13. The coastal flight took place on August 14 with a tide window between -0.7 and +0.5 foot. For the airborne LiDAR flight Tetra Tech subcontracted with Eagle Mapping. The data was acquired with a Riegl LMS VQ780i sensor.
• 2020-01-16 00:00:00 - Point Cloud Processing: The point cloud data was classified using the software tools Microstation, TerraScan and TerraModeler. Ground points were classified using a macro developed in-house. These points were then edited further manually to obtain the best bare earth representation. Water points were classified and edited using the hydro breaklines. Low, medium and high vegetation points were classified as per the following heights from the ground: low vegetation (0 to 0.6m), medium vegetation (0.6 to 1.5m), high vegetation (above 1.5m). Ignored ground points (class 20) were classified using 0.5m buffer distance from the hydro-breaklines. Bridge decks were identified using the surface file and classified accordingly. High and Low points were identified and classified into their respective classes. The point cloud data was finally tiled out in LP360 with the correct definition of the projected coordinate system. The point cloud has been classified using the following classes: Class Description Point Count Min Average Max Class 1 Default (11,419,873 points) Class 2 Ground (2,607,438,873 points) Class 3 Low_vegetation (1,631,352,621 points) Class 4 Medium_vegetation (151,567,537 points) Class 5 High_vegetation (1,039,793,650 points) Class 7 Low_point (840,222 points) Class 9 Water (145,165,821 points) Class 17 Bridge decks (870,198points) Class 18 High_noise (13,400 points) Class 20 Ignored Ground (867,734 points)
• OCM received 82 laz files from TetraTech. Data was received in UTM 10N NAD 83 (2011) meters horizontally and NAVD88 meters vertically. The data were classified as: 1 Default, 2 Ground, 3 Low_vegetation, 4 Medium_vegetation, 5 High_vegetation, 7 Low_point, 9 Water, 17 Bridge decks, 18 High_noise, Class 20 Ignored Ground. OCM processed all classifications of points to the Digital Coast Data Access Viewer (DAV). OCM performed the following processing on the data for Digital Coast storage and provisioning purposes: 1. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges. 2. Internal OCM scripts were run on the laz files to convert from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid12B model, to convert from UTM 10N NAD83 (2011) coordinates in meters to geographic coordinates, to assign the geokeys, to sort the data by gps time and zip the data to database and to http.

Data is available online for bulk or custom downloads

Data is backed up to tape and to cloud storage.