@natsock @rasterman you need the camera to take pictures of those inscriptions and show them to the zonai researcher in kakariko. not tauro, another guy. there's one on the ground at lookout landing that everyone is crowded around and that's how you start the side quest.
you can get the camera by progressing robbie's quest with the depths (where you get the paraglider) and then going to robbie's lab. he'll help you get the camera and ask you to take some photos of stuff.
the islands that have these inscriptions are easy to find once you unlock the full map by visiting all the towers. they're all shaped like flowers so they are visually distinct on the map.
Is there a way to unlock the sky map? The towers on land do nothing; but the light roots work. I haven't seen the sky equivalent.