This is ugly, to me. The casus is, if you map a circle, I do lots, often wastewater treatment plant clarifiers and roundabouts which the road managers here sprinkle around seemingly just for the fun of it in the oddest of places. When there has to be one, there is not even one long term planning, a spacious busy, long wait complex traffic lights controlled where the city does not seem to be able to reach the duh conclusion,
In JOSM you can simply use a 2 node straight line drawn over the diameter of the ring and then hit Shift+O to get your circle, then add the tags. If you do this for one with a 12 meter diameter object, JOSM makes a ring of 16 nodes, always. Just done one for a clarifier and then loaded this into the ID Editor to verify the issue. If you select this ring in ID and use the circularize function, it increases the ring nodes to 19. It depend on the size. Sometimes JOSM is satisfied with 8 nodes, practically an octagon. No, give it the ID treatment and it becomes 12 or more. This is not the end, BUT, there’s a catch. ID in it’s neat little way of achieving this ‘rounder’ ring actually goes about deleting some nodes from the original and then seems to be adding more to get to the rounder 19 on a 12 meter diameter ring. OK, don’t care, were it not that record is actually kept by OSM of how many nodes in an object were deleted and records them as reverts. The bananas question of course is, VAT ON ERTH.
JOSM Original, 16 nodes per the section pane view at right
ID Editor ‘augmented’, copied the original clarifier at top in the OSM database to below and hit right click menu, circularize function.
You need to count the nodes out in ID, not seen a place how many there are in an object, but a cursory look makes it obvious there more in the lower copied ring.
As said, who cares, were it not it does the dirty dance to delete part of the nodes first and then re circularizes. It is almost comical in that if you use the selective revert function in JOSM, you actually get on the first instance a circle with 2 flat sides, of the nodes that were actually kept before adding more, but for this case, head spinning did not actually save this and then demo the revert in JOSM. If you fancy, enjoy the Road runner trip.
(JOSM Does not screw around, draw that 12 meter ring by hand with 30 nodes and it will keep 30 nodes on hitting O. You could use the simplify function of course which I once did on a roundabout where a overzealous mapper thought 400 nodes was a top job… Some Mothers Do 'Ave 'Em )
