Adventures In Mapping

Great Lakes Bathymetry

Here is the result of a late afternoon diversion. The bathymetric data comes from the NOAA Great Lakes Environmental Research Laboratory. The aspect ratio is consistent with a 1920×1080 monitor so it might make an alright desktop image, if you are into that sort of thing.

Quick process run-down, which will take as long to type as it was to do…

The digital elevation model renders by default along a grayscale ramp from black (low) to white (high) elevation -and in this case, bathymetry.

Then in ArcGIS Pro’s raster functions I ran a hillshade to produce a shaded relief layer. I gave it a high-contrast mud color since the lake floors tend to be pretty gentle.

Then I made a copy of the raw DEM and gave it a color ramp of nearly-transparent slate (shallow, where you can see the hillshade below) to opaque cyan (deep, low-visibilty).

Then with a second copy of the same DEM I set elevations above lake level to a tan color and elevations below lake level I set to transparent. A poor-mans layer mask.