Add support for polygons in changefiles (as Ways)
#11
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| @@ -277,6 +288,10 @@ def _modify_existing_way(way_geom, way_id, nodes, tags, intersection_db): | |||
| """ | |||
| new_nodes = nodes.copy() | |||
| way_geom_pts = list(way_geom.coords) | |||
| if len(way_geom_pts) > WAY_POINT_THRESHOLD: | |||
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It seems like in cases where there are long ways this is going to end up creating a lot of noise, because ways by default are getting split at 2000 points, so this will create a warning for every way that gets split.
changegen/generator.py
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| ) | ||
| new_nodes.extend(nodes) | ||
| new_ways.extend(ways) | ||
| _global_node_id_all_ways.extend(chain.from_iterable([w.nds for w in ways])) | ||
| if isinstance(wgs84_geom, sg.Polygon): | ||
| # simple polygons can be treated like Ways. | ||
| if len(wgs84_geom.interiors) == 0: |
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A relation also needs to be created If the exterior is more than 2000 nodes, is this handled somehow?
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I didn't think of that. Does that mean anytime I split a long way into multiple ways I should create a relation joining them? I can see the case of a polygon exterior wanting to be a part of a multipolygon(?), that makes sense -- but what about regular Ways that are longer than 2000?
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Anytime a polygon gets split you need to create a multipolygon relation, which is confusing, because it's not a multipolygon, it's just a single polygon. But there is no polygon relation. Then you just apply the same tags to the relation that would have been applied to the way, and have no tags on the way.
It's more complicated for non-polygon ways. If you split a trail, the most correct thing to do is probably to create a route relation, but i think most of our current code knows how to deal with rejoining things if the rest of the attributes match, so the route relation is not strictly needed, and would probably be a waste of time to implement now.
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Was a little trigger-happy merging the |
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Cleaned up. |
This PR enables support for features of Polygon type to be exported from a conflation PostGIS database as OSM Closed Ways. Only support for
<create>nodes was added at this time, though modifications of Polygons might work but probably not and hasn't been tested.Description of Modifications
RelationandRelationMembernamedtuples tochangewritermoduleWayorRelationobjects to represent them depending on the complexity of the polygon (simple polygons: closed Ways; complex polygons w/ holes: Ways + Relation)Way(e.g. appending the first Node in the nodelist of the Way to the end of the Nodelist)--existing/-eargument optional to disable the search for intersections--max_nodes_per_wayoption and allows fornoneas a value.Potential Future Work
Because we've stopped ignoring polygon objects, we've opened the possibility that a given new object might intersect with a polygon. Creating
<modify>nodes to represent changes to existing OSM polygons that intersect with new objects is out of the scope of this PR. This is because it requires tooling to access the ID of a constituent Way that requires modifications, which requires modifications / requirements to the schema in the PostGIS database we're using.We've decided to not implement this, and have made an issue for it (#12).