# [postgis-users] Circle

Bob Pawley rjpawley at shaw.ca
Fri Jun 13 18:04:53 PDT 2008

```Thank you to all.

Bob

----- Original Message -----
From: <pcreso at pcreso.com>
To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
Sent: Friday, June 13, 2008 5:05 PM
Subject: Re: [postgis-users] Circle

> See ST_buffer at http://postgis.refractions.net/docs/ch06.html#id2594743
>
>
> Buffer generates a buffer zone around an existing geometry a specified
> distance out (or in if -ve) using a specified number of points. A buffer
> around a point is a circle if you use enough points, if you could buffer a
> point with 4 points, you'd get a square centred on the point instead of a
> circle.
>
>
> Cheers
>
>  Brent Wood
>
>
> --- On Sat, 6/14/08, Bob Pawley <rjpawley at shaw.ca> wrote:
>
>> From: Bob Pawley <rjpawley at shaw.ca>
>> Subject: Re: [postgis-users] Circle
>> To: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
>> Date: Saturday, June 14, 2008, 11:54 AM
>> 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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>> >>>
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```