On Sun, Feb 6, 2011 at 1:01 PM, Thibault North <tno...@fedoraproject.org> wrote: > In the mapping process (with JOSM or such tool), following roads is not really > a problem, especially when they are not too sinuous (and that's when the road > detector works well...). It can be done in a few clicks. Maybe the tool should > try and act differently (but that is more GUI/UI related), and we could > imagine > the following scenario: > - The user wants to map roads and selects a "road extraction" tool. > - He roughly follows a road, maintaining a click (as you would do to paint > with a brush in image processing softwares) > - The algorithm knows the approximate path, and tries to fit exactly the > center > of the road.
I think this would be the best way to do it. If an editor could perform each of the following operations with a single click or keystroke: - draw straight way segment from the last node to the mouse cursor - draw from the last node to the mouse cursor, following a perceived road - undo last automatically drawn section Or perhaps even the following: - advance from the last node a further X distance, following roads (where X is dependent on zoom level) ...then you have the makings of a very efficient process for tracing roads off imagery. The last operation above would let you keep hitting a key to advance a road until something goes wrong, then backtrack and fix it manually. What I saw in my testing was that most of the time (perhaps 70%) it got the road right, and sometimes it was just hopelessly wrong. That is presumably because the algorithm is determined that there *is* a road to find. It would be better for it to give up and not draw a road at all if its confidence isn't high. Steve _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
