[Proj] NTv2 info
Gerald I. Evenden
geraldi.evenden at gmail.com
Sun Jun 7 13:57:09 EST 2009
> In the case of the NGS NADCON files, an Intel machine can process them
> without byte flipping.
Did I write that? Hmmm. Sorry about that.
As NTv2 has been solved I reexamined the NADCON stuff which dates back to
the '80s with little updating on my part.
Given the current distribution of NGS NADCON, they deserve as many lashes with
wet noodles as the Canadians. C'mon, a file each for the
east-west/north-south correction. Only thing giving NGS points over the
Canadians was column order and negative longitude. No ethnogeodetic problems
I do not know where the NGS detailed description of the file format is but
they do distribute source code for routines reading the files. With effort
the format can be resolved from the FORTRAN code. It reminds one of the
principle deficiency of the FORTRAN language. It was the reason I often had
to resort to assembly in order to translate files into FORTRAN processable
It might even be an idea to translate the NADCON files into NTv2 but suspect
that overlapping areas with enhanced precision might not fit the scenario of
Maybe someone has already done it.
At least, it seems to be a good idea to build a directory file for the NADCON
distribution that summarized the regions and thus enhances lookup.
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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