# [postgis-users] Circle

Randall, Eric ERandall at eriecountygov.org
Sat Jun 14 07:29:38 PDT 2008

```Wouldn't that spawn anti-polygons in parallel universes? :-)

(I tried to think of something as clever as the "buttered cat array"
but it turns out that I'm not that clever.)

Eric

-----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 9:29 PM
To: pcreso at pcreso.com; PostGIS Users Discussion
Subject: Re: [postgis-users] Circle

So if I had a geometry (or collection of geometries) a buffer could be
established around those geometries such that they could be isolated from
further intrusion??

If sufficent buffers could be established around inhabited space only empty,
or near empty, space would remain?

In fact, a roving buffer could be established around empty space(s) to
continually identify those empty spaces???

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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>> >>>>
>> >>>
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