Great Lakes Bathymetry

Ideas

Process of creating a 3D map of the area

Resources

• Downloadable Great Lakes bathymetric maps from NOAA
• All bathymetric maps from NOAA
• The USGS Earth Explorer is easier to use than the above, but requires a login and download client
• Natural Earth provides shapefiles for cultural and physical elements

CNC Carve

Workflow

1. Download shapefiles from NOAA. Superior bathymetry contours with unclear provenance is available here, with login
2. Download and install QGIS and Inkscape
3. No need to extract files, open each in QGIS Desktop
4. Add OpenStreetMap information if desired (the native support is not working at this time, but the plugin does)
5. Right-click shapefile in left layers panel, select Properties
6. Choose Filter, then create expression, e.g. "DEPTH" IN ('0', '1', '25', '50', '60')

It is helpful to use the Values box (make sure "Use unfiltered layer" is checked if changing an applied filter) to see the extent of the map's values

Workflow Take 2

• Try this map with these instructions
• For OSM information, use Geofabrik.de and reformat if necessary as described here

3D Print

1. Download ArcGrid DEM from USGS National Map or Earth Explorer (3DEP, 1/3 arc-second DEM)
2. Unzip file
3. Open QGIS, add Vector, add layer file (.adf)
4. Select extent (Raster -> Extraction -> Clipper)
5. Save as GeoTIFF
6. Add GeoTIFF to model
7. Analyze to DEM (Raster -> Analysis -> DEM [Terrain Models])
   This step creates an apparently inaccurate model (top). Using 3DEM creates a more accurate representation, but the extent was smaller on the second.

   

   
   • If necessary, merge the DEMs
   • Solution to bathymetric (negative) altitude values: using Raster Calculator, add bottom value to all height values
8. Create STL (Raster -> DEMto3D)

A note on resolution.

Other Sources

• Earth satellite imagery from USGS, esp. those over time
• ArcGIS contour map of the Great Lakes
• Live Access Servers hosted by NOAA/PMEL/TMAP provide information on air quality, ocean salinity, temperature, etc.
• LIDAR resources in case we want to machine it. I want to machine it.
• BBBike.org pulls from OSM, but extent is much too small.
• Using plywood (though very heavy) with the proper scale would approximate the contour lines of a topo map...
• Mosaicing and clipping rasters
• OceansMap, a well-aggregated set of realtime data about major bodies of water around the world, including the Great Lakes region
• Historical maps from the Army Corps of Engineers
• Portal for Great Lakes Observing System information from the Integrated Ocean Observing system
• The National Map combines many of the above resources