[Mapserver-users] Help Request / datum shifts

[Kieran J. Ames]

First of all, my thanks to all who've offered assistance, guidance and
suggestions in this discussion.

Next: The discussion has been a learning (albeit humbling) experience, that
gives some perspective into the requirements necessary to actually capitalize on
(what now appears to be, more advanced) Mapserver functionality. It turns out
that in fact I was asking for a horse of a different color. Projecting data
sounded like its name. I didn't know projecting data with datum shifts was
different. I thought Proj support meant all Proj functionality.

Chip, you mention that "One option would be to put the windows compiled datum
shift files on the MapServer site along with the MapServer downloads.". Would
this be a "plug-n-play" way of attaining this datum shift functinality in a
Windows environment? Would one merely copy the datum-shift files into the
proj/nad directory and go forward making maps? Yes... I too see the possibile
reluctance. However, given my self-serving interests in availing myself of
different data sources, I would suggest that some way of accomplishing this
would benefit the community at large.

I'm also surprised that this kind of discussion hasn't happened in the past.
There are significant nuances to understanding data and datums and geography at
large that I wasn't even aware of. I looked through the archives in great
detail, but found nothing. (I should also add that given recent discussion, I
probably didn't put in correct search terminology... the things you never knew
you never knew!)

So, I'm back where I started, perhaps a little more knowledgable. I restate my
offer that if someone would help me make this go, I'd be happy to bring together
necessary documentation and data files for a beginning user that would chronicle
the problem and solution and enable them to reverse engineer themselves into
understanding.

Thanks again to everyone.
Kieran


"Hankley, Chip" wrote:

> > Actually, I'm now not sure about whether you'll need to
> > recompile or not.
>
> I think you do have to compile. ED, the files that you provided me when I
> was having trouble with this were some type of binary files. For instance,
> what is available from the PROJ4 site are the text based datum shift files:
>
> ALASKA
> CONUS
> ...etc.
>
> After compilation, there will be binary files of the same name, with the LLA
> extension:
>
> ALASKA.LLA
> CONUS.LLA
> ...etc.
>
> I think what I found was that simply having the text files in there was not
> enough... you had to have the LLAs (which you can only get by compiling).
>
> FWIW, these files have to be in two places if you're using BOTH cgi and
> php-mapscript. CGI looks for them in C:\proj\nad, and PHP-MapScript looks
> for them in c:\proj. I'm sure you could re-configure this at compile time,
> but, I typically use the pre-compiled binaries.
>
> Kieran, if you want, I can zip up my PROJ directory and e-mail it to you. In
> my opinion, we should put up a compiled version of the PROJ directory on the
> web site for windows users.
>
> Chip
> _______________________________________________
> Mapserver-users mailing list
> Mapserver-users at lists.gis.umn.edu
> http://lists.gis.umn.edu/mailman/listinfo/mapserver-users