[postgis-users] Buffering around 1/2 an object

[Picavet Vincent]

Hi,

> I known this sound like a strange question, but is it 
> possible to create a buffer around 1/2 of geomtry objectt.
> 
> If I choose to buffer round a stright line,  I get a geomtry 
> that looks like a  sausage,  if I buffer round a point,  I 
> get a geomtry that looks like a circle.
> 
> What I would like to do is buffer round only half an object, 
> in the case of a point I would like to get a semi circle, 
> buffer round a line, 1/2 a sausage!
> 
> Is this possible, any suggestions ?

Buffer the whole object,
Take the bounding box of the generated buffer
Cut the latest in half
Your <1/2 buffer> is the geometric intersection beetween the generated
buffer and its 1/2 bounding box.

As for the way of cutting the bbox, it's up to you to define a way since
you did not detail which half you wanted.
There may be other better ways of doing it, but this one will do the
job.
As a first optimization, you could first buffer half the object instead
of the whole one (and stay consistent with your definition of half).

Good luck,
Vincent

> 
> In the simultation that I am modeling, the data point/line 
> describe a starting point and I need to ensure that its 
> possible for traffic to leave the starting point on one side.
> 
> Dave.
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