[pgrouting-dev] Question about improving alpha shapes

[T S]

Hello,

For some projects I've been working on, I've had to make some
modifications to the alphashape method -
namely, allowing a custom alpha instead of just picking the optimal
regularly connected alpha, and allowing for disconnected multipolygons
instead of only returning a single polygon.

The use case that comes up is that some networks have holes or gaps in
the 2d plane. I.e., driving over a bridge, you can get to the
landmasses on either side of the bridge, but you can't really get to
all the water around the bridge. This water shouldn't be included in
the polygon.

I have an initial implementation of how this works, I have a few
questions about trying to contribute it in -
1.) Is there any interest in this feature? Or does pgRouting prefer
the current behavior?
2.) I noticed an earlier email thread discussing moving to
st_concavehull in postgis 2.0. While this would remove the dependency
on CGAL, st_concavehull doesn't appear to support returning multiple
disconnected geometries, and it's not really a true alpha shape.
3.) If there is interest in moving this in, where should I look to for
coding standards, and which parts of the API are 'stable' and which
aren't? in specific -
4) why does points_as_polygon return a setof geoms instead of just a geometry?
5) is it important for there to be both a points_as_polygon() and an
alphashape() function, or could the functionality be rolled up?

Thank you,
T

-- 
from talin
      "it's not stupid. it's advanced."