* Elliott Plack <elliott.pl...@gmail.com> [2016-01-07 20:12 +0000]: > What are the current accept[ed] best practices for determining where to "cut > off" the coastline and to begin a river or bay type feature? The wiki seems > to be in disagreement about this, and I've read chatter about switching to > ocean polygons.
I'm not sure I've seen a best practice, really, but I have in the past closed off rivers at their mouths and then tagged their (multi)polygons waterway=riverbank, tidal=yes. (Sometimes it can be difficult to tell where a river stops being tidal, but at least the Potomac doesn't have that problem.) My reasoning is essentially along the same lines as what to do when one river flows into another: at some point the smaller river ends and you could do worse than to draw a line across the mouth of that river and say, "Everything on this side is River A and everything on the other side is River B". Likewise, at some point, the ocean stops being the ocean (or the Chesapeake Bay stops being the Chesapeake Bay), so why not at the mouth of the river? Bays are a little more problematic, as there's not always as obvious a mouth as for a river, plus features like bays and coves can coexist with other features like rivers.[0] I usually leave bays as point features unless there's a really obvious delineation between them and everything else. I actually went through the work of cutting the Potomac off from the coastline of the Chesapeake Bay and turning it into riverbank multipolygons a few years ago, but JOSM crashed and lost my work before I was able to upload it and I felt too depressed to go back and redo everything. I believe I have since gone back and put in *some* riverbank multipolygons at the upstream end of the tidal region of the river. [0] I know according to some points of view, the entire Chesapeake Bay is just the lowest part of the Susquehanna River, but I'm pretty comfortable leaving the Bay as coastline. -- ...computer contrarian of the first order... / http://aperiodic.net/phil/ PGP: 026A27F2 print: D200 5BDB FC4B B24A 9248 9F7A 4322 2D22 026A 27F2 --- -- "I don't trust dreams." "They said they weren't dreams." "So? Dreams lie." -- "The Kindly Ones", Neil Gaiman ---- --- -- _______________________________________________ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us