Hi,
I use postgreSQL.8.4.2 and don't have postGIS installed.
I have a geometric type polygon and I know that it is possible to determine if a point it is inside or not of this polygon, using anything like that:
select polygon('(-23.5672,-46.6510),(-23.5670,-46.65095),(-23.5672,-46.6508),(-23.5672,-46.6510)') @> point('-23.567534,-46.64942')
The question:
Anyone knows an algorithm or have ideas how to determine if a point it is inside an area constructed by geometric type path expanded for a known distance?
Graphically:
the path
  Â  Â x=========x=======x
Â
the path expanded by a distance
ÂÂÂÂ Â ÂÂÂÂ |ÂÂÂÂÂÂÂÂ | AÂÂÂÂ |
ÂÂÂÂÂ Â Â Â |ÂÂÂÂÂ ÂÂ |Â ÂÂÂÂ |
 Â -------x=========x=======x------- C
ÂÂÂÂÂÂÂÂÂÂÂ
|ÂÂÂÂÂÂÂÂ | ÂÂ ÂÂ |
ÂÂÂÂÂÂÂ BÂÂ |ÂÂÂÂÂÂÂÂ | ÂÂÂÂÂ |
the points A and B are inside and the point C are outside .
Suggestions are welcome.
Thanks in advance,
Josi Perez
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