[Proj] NTv2 info

Cuinet Jérôme jerome at georezo.net
Tue Jun 2 14:14:37 EST 2009

We can see the existence of a NTV2 Developer's Guide Junkins and Farley, 
1995, but any link is broken. The closest document is a NTV2 User's Guide 
that you have pointed.

This developper guide must be on some computers...

How silly we are, using a canadian built-in format. Fortunately it wasn't an 
Autralian format ! By talking australians, they noticed that NTv2 format had 
seemed to be compiler dependant, although it is finally not compiler 
dependant : http://www.geom.unimelb.edu.au/gda94/NTv2_Binary.pdf

----- Original Message ----- 
From: "Gerald I. Evenden" <geraldi.evenden at gmail.com>
To: "PROJ.4 and general Projections Discussions" <proj at lists.maptools.org>
Sent: Tuesday, June 02, 2009 7:57 PM
Subject: [Proj] NTv2 info

> Kudos to the Swiss---so far they are the only ones that seem to have 
> format
> information on the NTv2 correction files.
> A slap on the face with cold, wet noodles to the Canadians because I 
> cannot
> locate any format details on the Canadian NTv2 distribution file.  The 
> only
> thing I can find is the documenation of a program to access the file, 
> which
> deserves another slap for not being available in source form.
> I seem to get the idea that the Canadians developed this format---comments
> please---and if they did then the designers deserve to be flogged for 8 
> days
> with wet noodles for "positive east longitude."  I can't believe it!!!! 
> What
> is unbelievable arrogance by whoever had that stupid---yes, *VERY*
> stupid---idea.  I was looking at the headers of a Swiss NTv2 file and sure
> enough, negative values for longitude.  What's in that Molson anyway?  The
> McKenzie brothers must have been co-chairing the development commitee.
> An intersting aside demonstrated by the Swiss distribution: the compress 
> version of the NTv2 file is slightly smaller than the binary version.
> Wouldn't it have been nice if the McKenzie brothers looked into this when
> spec'ing the output form and saved everyone from the curse of determining
> endian conversion?
> There is a problem with the Swiss documentation: it is in German and the
> details of the data records is not as clear as the headers.
> Obviously, I have not exhausted all possible 4,000 google hits in looking 
> for
> documentation.  If someone is aware of a defining english pdf somewhere,
> please let me know.  Thanks.
> -- 
> The whole religious complexion of the modern world is due
> to the absence from Jerusalem of a lunatic asylum.
> -- Havelock Ellis (1859-1939) British psychologist
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