2022 NOAA Topobathy Lidar DEM: Morro Bay, CA

Create custom data files by choosing data area, map projection, file format, etc. A new metadata will be produced to reflect your request using this record as a base.

Bulk download of data files in the original coordinate system.

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.

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.

This lidar report provides accompanying information about the collection and processing of this lidar data set.

Data for the Morro Bay 2022 Topobathymetric Lidar project area was acquired by NV5 Geospatial (NV5) using Riegl VQ-880-GII topobathymetric Lidar systems. All derived DEM data is referenced to:

Horizontal Datum-NAD83(2011) epoch: 2010.00

Projection-UTM Zone 10N

Horizontal Units-meters

Vertical Datum-NAVD88 (Geoid12b)

Vertical Units-meters

The collected Lidar data were immediately processed by NV5 to a level that allowed QA/QC measures to determine if the sensor functioned properly and to assess the coverage of submerged topography. The initial files were inspected for sensor malfunctions and then passed through automated raster generation to develop an initial assessment of bathymetric coverage. NV5 reviewed all acquired flight lines to ensure complete coverage and positional accuracy of the laser points.

NV5 resolved kinematic corrections for aircraft position data in PosPac MMS 8.5 using aircraft GNSS and Applanix's proprietary PP-RTX solution. This was used to correct the continuous onboard measurements of the aircraft position recorded throughout the flight. A final smoothed best estimate trajectory (SBET) was developed, blending post-processed aircraft position with attitude data. Using the SBETs, sensor head position and attitude were then calculated throughout the survey.

Following final SBET creation, NV5 used RiUnite 1.0.1 to calculate laser point positioning by associating SBET positions to each laser point return time. The speed of light and its direction of travel is changed or refracted when entering the water column from air. A refraction correction was applied to account for this difference by adjusting the depth (distance traveled) and horizontal positioning (change of angle/direction) of all submerged points in the Lidar data. TerraSolid v19 and NV5's proprietary software LasMonkey were used to classify water surface points and derive water surface models. Separate models were created for each scanner of each collected swath to ensure temporal differences and wave or water surface height variations between flight lines were accurately accounted for when applying the refraction correction to the submerged data. These models, along with the Lidar points and the SBETs, were processed in LasMonkey's refraction tool to accurately adjust the positioning of bathymetric points. Using raster-based QC methods, the output data were verified to ensure the refraction tool functioned properly.

Once all submerged points were refracted by flight line, data were exported to LAS 1.4 format and combined into 500 m x 500 m tiles. NV5 used custom algorithms in Terrascan v19 to classify the initial ground/submerged topography surface points. Data were then further calibrated using StripAlign 2.1 based on classified hard surface areas of swath overlap. Relative accuracy was compared and verified through the use Delta-Z (DZ) orthos created using NV5's Las Product Creator. Absolute vertical accuracy of the calibrated data were assessed using ground survey data and complete coverage was again verified.

After a final automated classification, NV5 then performed manual editing to review all classification and improve the final topobathymetric surface. NV5's LasMonkey software was used to update LAS header information, including all projection and coordinate reference system information. The final Lidar data are in LAS format 1.4 and point data record format 6.

The final classification scheme is as follows:

1 - unclassified

1O - edge clip

2 - ground

7W - low noise

9 - NIR water surface

18W - high noise

40 - bathymetric bottom or submerged topography

41 - Green water surface

45 - water column

The topobathymetric bare earth DEMs were output at 1 meter resolution in GeoTIFF format into 96 500 m x 500 m tiles. The Morro Bay 2022 rasters are clipped to the extent of the project boundary and named according to project specifications.

A bathymetric void shapefile was created to indicate areas where there was a lack of bathymetric returns. This shape was created by triangulating bathymetric bottom points with an edge length maximum of 4.56m to identify all areas greater then 9 square meters without bathymetric returns. This shapefile was used to clip and exclude interpolated elevation data from these areas in the bathymetric void clipped topobathymetric bare earth model.

The NOAA Office for Coastal Management (OCM) received 96 digital elevation model (DEM) files in GeoTiff format from NV5 Geospatial. The bare earth raster files were at a 1 m grid spacing. The data were in UTM Zone 10N NAD83 (2011), meters coordinates and NAVD88 (Geoid12B) elevations in meters. OCM assigned the appropriate EPSG codes (Horiz - 6339, Vert - 5703) and copied the raster files to https for NOAA Digital Coast storage and provisioning purposes.

In February of 2023, NV5 Geospatial sent three replacement files for existing files. These files were:

1. MRR22_038

2. MRR22_046

3. MRR22_055

The point files that correspond to these DEM files were reclassed to include points that were changed from 1 - Unclassified to Class 43 - Submerged Object, not otherwise specified (For Morro Bay, oyster reefs have this classification, even though exposed at low tide). The new DEMs reflect that change. These files were processed to replace the existing files of the same name.

The NOAA Office for Coastal Management (OCM) received 3 digital elevation model (DEM) files in GeoTiff format from NV5 Geospatial. The bare earth raster files were at a 1 m grid spacing. The data were in UTM Zone 10N NAD83 (2011), meters coordinates and NAVD88 (Geoid12B) elevations in meters. OCM assigned the appropriate EPSG codes (Horiz - 6339, Vert - 5703) and copied the raster files to https for NOAA Digital Coast storage and provisioning purposes.