[postgis-users] Circle

[Michael Smedberg]

FYI, you can find some documentation on ST_Buffer at
http://postgis.refractions.net/docs/ch06.html

It reads:

ST_Buffer(geometry, double, [integer])

    Returns a geometry that represents all points whose distance from
this Geometry is less than or equal to distance. Calculations are in the
Spatial Reference System of this Geometry. The optional third parameter
sets the number of segment used to approximate a quarter circle
(defaults to 8).

    Performed by the GEOS module

    Do not call with a GeometryCollection as an argument

    OGC SPEC s2.1.1.3

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Bob
Pawley
Sent: Friday, June 13, 2008 4:54 PM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] Circle

Is that the only function of the buffer - to create a circle?

Can the buffer modify other functions. If so - what is the criteria?

Bob
----- Original Message ----- 
From: "Paul Ramsey" <pramsey at cleverelephant.ca>
To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
Sent: Friday, June 13, 2008 4:33 PM
Subject: Re: [postgis-users] Circle


> Try it and see :)
> It constructs a circular-shaped polygon around the point.
> P
>
> On Fri, Jun 13, 2008 at 4:23 PM, Bob Pawley <rjpawley at shaw.ca> wrote:
>> I'm interested in what the buffer actually does.
>>
>> Bob
>>
>> ----- Original Message ----- From: "Paul Ramsey" 
>> <pramsey at cleverelephant.ca>
>> To: "PostGIS Users Discussion"
<postgis-users at postgis.refractions.net>
>> Sent: Friday, June 13, 2008 3:46 PM
>> Subject: Re: [postgis-users] Circle
>>
>>
>>> ST_Buffer(ST_MakePoint(x,y),r)
>>>
>>> On Fri, Jun 13, 2008 at 3:35 PM, Bob Pawley <rjpawley at shaw.ca>
wrote:
>>>>
>>>> What is the best way of creating a circle?
>>>>
>>>> Mu PostgreSQL Developes Handbook susy it should be - point and
radius.
>>>>
>>>> Postgis doesn't seem to have this function.
>>>>
>>>> Bob
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