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Oceans, plus I guess the Caspian Sea, don’t get much satellite coverage because no one (except militaries) wants it enough. For the ocean, Google Maps uses bath
by pxeger1 2y ago
Oceans, plus I guess the Caspian Sea, don’t get much satellite coverage because no one (except militaries) wants it enough. For the ocean, Google Maps uses bathymetry data to synthesise shaded blue imagery. The Caspian in particular I guess is such a uniform colour either because it’s so shallow that Google’s shading algorithm doesn’t shade it at all? (Compare to the northwesternmost parts of the Adriatic Sea, for example)
- jcrawfordor 2y agoA big issue here too is the image stitching; aerial images are registered for big tile maps based in part on feature analysis of the edges and that just never works right for images of the ocean (mostly you have waves, and they're in different places in each image). Even if you register it perfectly the waves ensure that the edges will still have stitching artifacts. As a result the "false color" oceans that Google Maps shows just look better than actual imagery. The "imagery" source for the oceans in Google Maps is (or at least was) GEBCO, it's a global bathymetric dataset made by registering depth sounding tracks from mostly commercial vessels. I thought maybe GEBCO didn't cover the caspian sea but it looks like it does for the last decade or so, but admittedly it seems to be data from just one survey and it's tagged as limited quality (at least in older versions of the dataset), so maybe Google ignores it.