[Proj] Hi

[Mikael Rittri]

Hello,
"Gauss conformal" means the same thing as "Gauss-Krüger" or "Transverse Mercator". 
With the central longitude 23°E, it looks like a national definition. 

I looked for "23" in the pcs.csv file that is shipped with GDAL.  
Assuming that your coordinate reference system is included in the EPSG dataset, 
I think it must be one of these: 

  CODE        NAME                          AREA OF USE
  EPSG:2050,  "Hartebeesthoek94 / Lo23",    South Africa 22°E to 24°E
  EPSG:2075,  "ELD79 / Libya zone 12",      Libya 22°E to 24°E
  EPSG:3130,  "ETRS89 / ETRS-GK23FIN",      Finland 22.5°E to 23.5°E
  EPSG:3197,  "LGD2006 / Libya TM zone 12", Libya 22°E to 24°E
  EPSG:22283, "Cape / Lo23",                South Africa 22°E to 24°E 
  EPSG:29383, "Schwarzeck / Lo22/23",       Namibia 22°E to 24°E

Probably, only some of these datums can be considered to be equivalent 
to WGS84, so you can rule out those with other datums. 
You can find the details of the datums and the projection parameters 
on www.epsg-registry.org or on http://spatialreference.org .

To implement the south-oriented Transverse Mercator used in South Africa, you 
may need to use a negative scale factor (use +k=-1 instead of +k=1 ) in Proj.4.

Good luck,
--
Mikael Rittri
Carmenta AB
SWEDEN
www.carmenta.com

-----Original Message-----
From: proj-bounces at lists.maptools.org [mailto:proj-bounces at lists.maptools.org] On Behalf Of Pieter Bosch
Sent: den 17 mars 2009 13:04
To: PROJ.4 and general Projections Discussions
Subject: Re: [Proj] Hi

Hi,

I've seen your text, and its been very help full.

I was asking this question because I've got a military map in my possession that states that it is in a Gauss Conformal projection and that the central meridian is at 23*East and also using wgs84 spheroid.

That central meridian of 23*East is not an interval of a Central meridian of a 6* or 3* zone width system 



 

-----Original Message-----
From: proj-bounces at lists.maptools.org [mailto:proj-bounces at lists.maptools.org] On Behalf Of Mikael Rittri
Sent: 17 March 2009 12:59 PM
To: PROJ.4 and general Projections Discussions
Subject: Re: [Proj] Hi

Pieter wrote:

> I've got some information from the web that indicates that Gauss-Kruger divides zones of width 3*. 
> I also found text saying its is the same as UTM with zones of 6* and that only the scale factor changes to 1.0 . Does any one know the real answer?

Both conventions exist, and a few more national ones.
See http://www.cartotalk.com/lofiversion/index.php?t3633.html for a discussion, and some more links.  
In summary, if someone says "Gauss-Krüger zone number n", then you have not the slightest idea what it means... 

Best regards,
--
Mikael Rittri
Carmenta AB
SWEDEN
www.carmenta.com 

 _______________________________

From: proj-bounces at lists.maptools.org [mailto:proj-bounces at lists.maptools.org] On Behalf Of Pieter Bosch
Sent: den 17 mars 2009 11:05
To: proj at lists.maptools.org
Subject: [Proj] Hi

Need some info.

I've got some information from the web that indicates that Gauss-Kruger divides zones of width 3*. I also found text saying its is the same as UTM with zones of 6* and that only the scale factor changes to 1.0 . Does any one know the real answer?

If I do a UTM with a scalefactor of 1.0 will that be a gauss kruger projection? 

Anyone?

thanks 

_______________________________________________
Proj mailing list
Proj at lists.maptools.org
http://lists.maptools.org/mailman/listinfo/proj
_______________________________________________
Proj mailing list
Proj at lists.maptools.org
http://lists.maptools.org/mailman/listinfo/proj