Hello, Some of you may have already seen this question on http://gis.stackexchange.com [1], sorry for this. I've been suggested to ask my question here, so here I am...
I am translating an input that describes zones by mixing segments and arcs. Arcs are given by a center, 2 points (beginning/end of arc) and a direction (CW or CCW). In a first prototypes using GDAL, I inspected once how the points were sorted after the call to .buffer() and made the assumption that they will always be in the same direction. Then I moved my code to shapely, and it looks like the direction used is not the same, so I'm back to inspecting and hardcoding the internal direction. But my guess is that this is not the correct way of dealing with circle direction. Should I check after every calls to .buffer() the direction in which the points are ordered ? If so, is there a well known method to compute the direction ? I guess I could "easily" compute from 3 points the direction of the points. But maybe there is already something existing ? Since this question, I've had more problems, in particular regarding invalid geometries (see this other question[2]). Some of my polygons are self-intersected and I'm trying to correct these so that I can use shapely operations (intersect, union, etc). I've seen that in some case, using buffer with a very short radius fixes the problem. But in some case, the polygon ends up completely wrong. For example, the attached wkt has a single invalid polygon (it intersects near the start/end of the arc). Using buffer will create a flat polygon that is not really what I would expect. Is there any "common" way to correct such problem ? Thanks for any hint you can give :) I'm really fine with reading documentation & whatever, but I could not find anything regarding this. Marc PS: all the code is available here : https://github.com/dkm/airspace-checker [1]: original question: http://gis.stackexchange.com/questions/5862/how-to-deal-with-direction-cw-ccw-of-circles-in-particular-with-shapely [2]: http://gis.stackexchange.com/questions/5978/why-is-this-polygon-self-intersected-and-invalid _______________________________________________ Community mailing list [email protected] http://lists.gispython.org/mailman/listinfo/community
