Often I find the best way of understanding something is to try to imagine its opposite. There’s probably a word for that in the field of rhetoric, but I don’t know what it is. So I’ll just imagine that I do.
In the past couple of weeks I’ve been asked by two different folks about how to invert the elevation of Earth, such that oceans were mountains and mountains were oceans. Marek Doršic, of ArcGEO in Slovakia, said that his daughter had this question. So my daughter Sparrow and I endeavored to try it out…
Ok, here is the gist, my friends! Grab your digital elevation model (I used a DEM from the magnificent GEBCO team) and use the “negate” raster function to reverse the values. In the resulting image, the highest elevations are now the lowest, and vice-versa. Then you can whip up a custom color gradient to paint in the bathymetry (which used to be dry land) and topography (which used to be under water) to taste. Then, if you are feeling adventurous (and if you’ve come this far then of course you are) you can convert your map into a 3D global scene, make a copy of the inverted elevation, the drag that into the surface layer group to assign the 3D vertical texture to your wacky reversed elevation. Then explore our inside-out world with someone who is sparkling with curiosity and insights.
Love, John and Sparrow