[GRASS5] datum shifts

[Bernhard Reiter]

On Fri, Apr 19, 2002 at 01:02:16PM -0700, rgrmill at rt66.com wrote:

> > It is hard for me to judge if this might be a cause for more bugs 
> > or can be savely done. 
> > We have the possibility to schedule this addition for 5.0.1
> > depending on the answer.
> 
> The changes in the user modules are fairly small, so I don't anticipate 
> this will spin off a lot of new bugs.  But then, I'm an optimist.

Okay, try to get it in.

> Installation bugs are another matter.  I don't know much at all about 
> configure or make, so someone else will have to estimate the chance of 
> introducing installation bugs.

I can't see that this will result in too big installation hassles.
Otherwise we have to sort it out.

> > What does " They have to be interpreted to binary by a program" mean?
> 
> The tables are delivered in plain text.  The proj library functions read 
> them in a binary format.  There is a program in the proj-4.4.5 library 
> called nad2bin that performs the function of reading the ascii tables 
> and rewriting them in the format that the library functions need.  That 
> will have to be taken care of during GRASS installation.  

Shouldn't this be done at GRASS compile time, so to have the
right binary tables for the platform?
Or will the format change with proj library versions
that have the same binary interface?

> After installation the nad2bin code is only necessary 
> if the tables are later updated.

Sounds even more like a step done on GRASS compilation.

> I think the data tables 
> have to go under $GISBASE somewhere.  

That is not hardcoded, though...
It providing an option to specify a non-default path a good idea?

> Wherever they do go has to be 
> coded into the proj library.

This confuses me a bit, is it an addition to proj then?


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