[Proj] proj=undef ??

support.mn at elisanet.fi support.mn at elisanet.fi
Tue Jun 21 13:43:19 EST 2011


Mikael,

simply since you don't need any prjection to do
datum calculations.

Janne.

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

Mikael Rittri [Mikael.Rittri at carmenta.com] kirjoitti: 
> Hello Janne,
> if I understand you right, what you want is impossible.  
> 
> If the projection is unknown, any input coordinates 
> will be non-georeferenced. So, how could the datum shift
> machinery do anything on coordinates that cannot be
> interpreted? 
> 
> Maybe I misunderstand what you want to do.
> 
> Mikael Rittri
> Carmenta
> Sweden
> http://www.carmenta.com
> 
> -----Original Message-----
> From: proj-bounces at lists.maptools.org [mailto:proj-bounces at lists.maptools.org] On Behalf Of support.mn at elisanet.fi
> Sent: den 19 juni 2011 12:30
> To: proj at lists.maptools.org
> Subject: [Proj] proj=undef ??
> 
> Hello,
> 
> there is a need to have an undefined projection with possible datum shift like:
> 
> proj=undef
> ellps=bessel
> towgs84=.....
> no_defs
> 
> That would then transfer the projection input to output without doing any forward or inverse calculations even if those routines called but allowing datum shifting.
> 
> So the absolutely minimal definition would be
> 
> proj=undef
> datum=undef
> 
> or shorter version
> 
> proj=undef
> 
> and that would feed all input directly to the output. Those switches would allow the end user to control the handling of the data.
> 
> So the "proj=undef" is same as not doing anything by the projection library if called but not giving any error messages about missing projection but doing all datum shifting if requested. Any ideas?
> 
> Regards: Janne.
> 
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