[postgis-users] postgis-users Digest, Vol 43, Issue 21

Sun May 21 14:38:45 PDT 2006

Paul, thanks for your reply.
I saw the function distance_sphere but not the length_sphere.
Is there a function called length_sphere? 
Thanks
Fermín

-----Mensaje original-----
De: orkun [mailto:temiz at deprem.gov.tr] 
Enviado el: Sunday, May 21, 2006 18:20
Para: postgis-users at postgis.refractions.net
Asunto: [postgis-users] postgis-users Digest, Vol 43, Issue 21

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Today's Topics:

    1. Length, distance, area using SRID 6326 (Ferm?n Pieri)
    2. Re: Length, distance, area using SRID 6326 (Paul Ramsey)
    3. polygon width (orkun)
    4. Re: polygon width (Paul Ramsey)

----------------------------------------------------------------------

Message: 1
Date: Sat, 20 May 2006 18:18:23 -0300
From: Ferm?n Pieri <fpieri at faster.com.uy>
Subject: [postgis-users] Length, distance, area using SRID 6326
To: "'postgis-users at postgis.refractions.net'"
	<postgis-users at postgis.refractions.net>
Message-ID: <7EFC8543031AD911A7940004AC96C65E02011C at NETCOM01>
Content-Type: text/plain;	charset="iso-8859-1"

Hi, I am using SRID 6326 as the spatial reference id of the geom column. But
when i try to use length, distance and area functions, the results are not
what i expect (of course, using spherical calcultations) Any idea? Opengis
specification says that this functions return the result using the SRID of
the geom column. Why postgis include distance_sphere, length_spheroid, etc.?
I tried length_spheroid and the result is what i need but it takes a long
processing time. I will appreciate somebody's help

Thanks

Fermin

------------------------------

Message: 2
Date: Sat, 20 May 2006 20:57:36 -0700
From: Paul Ramsey <pramsey at refractions.net>
Subject: Re: [postgis-users] Length, distance, area using SRID 6326
To: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
Message-ID: <616D36E8-09BC-4ECC-BD28-5BE62CEBAF43 at refractions.net>
Content-Type: text/plain; charset=ISO-8859-1; delsp=yes; format=flowed

There is no help to give, you have all the pieces in front of you. If your
reference system is in spherical coordinates and you do not want to do a
transform() to a planar system, use the _sphere or _spheroid functions.
_sphere is faster than _spheroid, but less accurate -- you may find it is
well within the tolerances you need however.  Spheroid calculations are very
expensive, nothing to be done about that (difference between a converging
set of differential equations and a simple trig formula).

P.

On May 20, 2006, at 2:18 PM, Fermín Pieri wrote:

> Hi, I am using SRID 6326 as the spatial reference id of the geom
> column. But
> when i try to use length, distance and area functions, the results  
> are not
> what i expect (of course, using spherical calcultations) Any idea?  
> Opengis
> specification says that this functions return the result using the  
> SRID of
> the geom column. Why postgis include distance_sphere,  
> length_spheroid, etc.?
> I tried length_spheroid and the result is what i need but it takes  
> a long
> processing time. I will appreciate somebody's help
>
> Thanks
>
> Fermin
> _______________________________________________
> postgis-users mailing list postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users

------------------------------

Message: 3
Date: Sun, 21 May 2006 14:21:19 +0300
From: orkun <temiz at deprem.gov.tr>
Subject: [postgis-users] polygon width
To: postgis-users at postgis.refractions.net
Message-ID: <44704D2F.60502 at deprem.gov.tr>
Content-Type: text/plain; charset=ISO-8859-9; format=flowed

hello

I want to know how I can calculate widths of polygons via postgis command

regards

-- 
Ahmet Temiz
Jeoloji Müh.
Afet Ýþleri Genel Müdürlüðü
Deprem Araþtýrma Dairesi
Tel: (312) 287 89 51 veya (312) 287 26 80/1547
Faks: (312) 287 89 51
E. Posta: temiz at deprem.gov.tr
  www.deprem.gov.tr

Ahmet Temiz
Geological Eng.
General Directorate of Disaster Affairs
Earthquake Research Department
Phone: +90 (312) 287 89 51 or (312) 287 26 80/1547
Fax: +90 (312) 287 89 51
E. Mail: temiz at deprem.gov.tr
www.deprem.gov.tr

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------------------------------

Message: 4
Date: Sun, 21 May 2006 09:17:46 -0700
From: Paul Ramsey <pramsey at refractions.net>
Subject: Re: [postgis-users] polygon width
To: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
Message-ID: <1167274E-80AA-4E28-961F-617F6347FB20 at refractions.net>
Content-Type: text/plain; charset=UTF-8; delsp=yes; format=flowed

What is the "width" of a polygon?  Maximum straight line diameter? What if
it crosses a hole?  Diameter along a particular axis or direction?

***Say, polygons are similar to rectangles. I want to know the values of 
***their short sides.
***these polygon  don't have any hole in them.

regards

Ahmet Temiz

P

On 21-May-06, at 4:21 AM, orkun wrote:

> hello
>
> I want to know how I can calculate widths of polygons via postgis
> command
>
> regards
>
> --
> Ahmet Temiz
> Jeoloji MÃ¼h.
> Afet Ä°ÅŸleri Genel MÃ¼dÃ¼rlÃ¼ÄŸÃ¼
> Deprem AraÅŸtÄ±rma Dairesi
> Tel: (312) 287 89 51 veya (312) 287 26 80/1547
> Faks: (312) 287 89 51
> E. Posta: temiz at deprem.gov.tr
> www.deprem.gov.tr
>
> Ahmet Temiz
> Geological Eng.
> General Directorate of Disaster Affairs
> Earthquake Research Department
> Phone: +90 (312) 287 89 51 or (312) 287 26 80/1547
> Fax: +90 (312) 287 89 51
> E. Mail: temiz at deprem.gov.tr
> www.deprem.gov.tr
>
>
> --
> This message has been scanned for viruses and
> dangerous content by MailScanner, and is
> believed to be clean.
>
> _______________________________________________
> postgis-users mailing list postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users

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