Hi,
Would http://postgis.net/docs/ST_ShortestLine.html help you in this case?
I am not sure how important the distinction between left/right is, but
are you sure that this is always defined properly just by looking at the
street and building only? E.g. if you have the following: the house (in
the center) is it on the left or right of the small dead end street?
+-------------------+
| |
| +===+ |
| +===+ |
| |
| + |
| | |
+----+--------------+
One option: You could build explicit topology and then use information
of the faces and use left/right pointers on the edges (the streets) to
determine that a building is on the left/right of a street (road part) -
you can then also easily filter dead ends.
Another (potentially less accurate) option: calculate orient2d
(https://www.cs.cmu.edu/~quake/robust.html) for every segment of the
street to every polygon vertex of the building (or even coarser
approximation, but much faster: use centroid of the house and one
segment that represents the street, e.g. vector from begin point segment
- end point segment). I think you have to make such an orientation test
in Postgres/PostGIS yourself by making a custom database function. Note
that this could give wrong results when streets run around buildings
(flipping of left/right as result).
Martijn
On 23-11-15 16:13, toni hernández wrote:
Hello everyone,
I have two tables: streets and buildings.
streets with a linestring geometry and buildings with polygons geometry.
I need to know what is the minimal distance from each street to a
building on the right, and then, what is the minimal distance from the
street to a building on the left.
Any ideas on how I should approach this?
Thank you!
--
*Toni Hernández Vallès*
Servei de Sistemes d'Informació Geogràfica i Teledetecció
-
Universitat de Girona
*SIGTE*
-
Pl. Ferrater Mora 1
17071 Girona
Tel +34 972 418 039 (7026 intern)
[email protected] <mailto:[email protected]>
http://www.sigte.udg.edu
Twitter http://twitter.com/SIGTE_UDG
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