2010 USACE NCMP Topobathy Lidar DEM: Oregon and Washington

Oregon dates of collection.

Washington dates of collection.

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Information on the NOAA Office for Coastal Management (OCM)

The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

This graphic displays the footprint for this lidar data set.

Link to custom download, from the Data Access Viewer (DAV), the lidar point data from which these raster Digital Elevation Model (DEM) data were created.

These data were collected using the SHOALS-1000T and ALS60 systems. They are owned by Fugro and operated through contract. The ALS60 system collects topographic lidar data at maximum pulse rate of 200 kHz in a wavelength of 1064 nm with a CASI-1500 hyperspectral line scanner integrated with the system. The SHOALS collects bathymetric lidar data at 1kHz, RGB imagery at 1Hz and a CASI-2 hyperspectral line scanner integrated with the system as well. Aircraft position, velocity and acceleration information are collected through a Novatel and POS A/V 410 equipment (SHOALS) and the onboard GPS/IMU system (ALS60). SHOALS raw data streams are transferred to the office for downloading and processing in SHOALS GCS software. ALS60 raw data were also transferred to the office and processed in IPAS software. Aircraft position data are processed using POSPac software and the results are combined with the lidar data to produce 3-D positions for each lidar shot. Upon inspection and QA/QC in the software packages Fledermaus (SHOALS), GeoCue and TerraScan (ALS60), anomalous data are flagged as invalid. FPI Workbench and Fugro's proprietary software convert all valid data from ellipsoid to orthometric heights based on the NGS' GEOID09 model and exports data as a series of first return topography and bathymetry ASCII files. The bathymetry files contain only the returns below the water surface (no topography).

The topographic first return and bathymetry point clouds, where both exist, are combined into a single file to create a surface model grid (DSM); bathymetric data have been limited to data below the water surface. On bare earth DEM, topographic data has been filtered to include ground returns only; These datasets are combined to create the elevation model.

The raster grids are created by generating a triangulated irregular network (TIN) and then extracting the grid node elevations from the TIN surface; in the bare earth DEM, interpolation fills in elevation values over building footprints. The origin point of the grid is located at a horizontal position whose value is evenly divisible by the 1m grid resolution such that rasters from subsequent surveys have common cell boundaries. Fugro uses FPI Workbench and ArcGIS to perform this operation utilizing TIN area delineation method: "max edge length 10m"; this also secures elevations will not be interpolated more than 5m away from actual data points (except when interpolating over building footprints). The grid is converted to a TIFF raster within ArcGIS. The projection is defined as "North American Datum of 1983" using the DefineProjection command within ArcToolbox; statistics are also generated with Calculate_Statistics tool to display the grid's elevations range properly.

Horizontal positions, provided in decimal degrees of latitude and longitude, are referenced to the North American Datum of 1983 (NAD83). Vertical positions are referenced to the NAD83 ellipsoid and provided in meters. The National Geodetic Survey's (NGS) GEOID09 model is used to transform the vertical positions from ellipsoid to orthometric heights referenced to the North American Vertical Datum of 1988 (NAVD88).

The NOAA Office for Coastal Management (OCM) received GeoTiff format files from USACE JALBTCX for the Oregon and Washington coastline project area. The bare earth raster files were at a 1 m grid spacing. The data were in geographic NAD83 coordinates and NAVD88 (Geoid09) elevations in meters. OCM assigned the appropriate EPSG codes (Horiz - 4269, Vert - 5703) and copied the raster files to https for Digital Coast storage and provisioning purposes.