[GRASS-PSC] grass code making its way into gdal (+relicense)

[Hamish]

Dylan:
> I do not think that this act was intentional.
Massimiliano:
> I also don't think this was intentionally done

Nor, I. He was quite up front about the code heritage on his site; I
consider this to be simply an oversight in the source code header
comments which then caused another problem downstream. He undertook
it partly as a learning experience, and I guess that's what it turns
out to be. :) We all learn our lessons from time to time.

I fully understand that assuming a port from libgrass to libgdal and
C to C++ is not a verbatim copy so is ok seems reasonable at first,
but if you read the text of the GPL2 license it is rather clear:

"2b) You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any
part thereof, to be licensed as a whole at no charge to all third
parties under the terms of this License."


I do not wish to assign any blame or give anyone a hard time, just
to fix the technical problem so this nice tool can be cleanly released
to the public.


Hamish:
> > It is pretty clear that the core methods of gdaldem were directly
> > derived from a GPL work.
Markus:
> Are you really sure, Hamish?

Yes, I am, although perhaps I should have thrown in the word
"unintentionally". -- but that is irrelevant to the truth of the
statement.

gdaldem is based on Matt's Apache licensed version. Matt's code was
derived from ~ GRASS 5.0.2-6.2.1 (GPL) and (for whatever reason) ended
up relicensed without attribution under the Apache license. That is what
my above statement refers to.

That GRASS 5,6's version itself was based on a public domain work, and
that we are able + willing to mention and now help verify that fact, is
purely a matter of coincidence and good luck.




update:
Even, Helena, and myself have now looked through the old CERL version
dug up by Markus. Even found one one item in r.slope.aspect but as
far as I can tell that's in the CERL version already -- awaiting
clarification. As far as r.shaded.relief goes there is a small
contribution from Michael and one from Gordon Keith that are probably
trivial but as to what constitutes a trivial change isn't for me to say,
so I've asked them anyway. Other than that everything seems to be in
the clear, thankfully.

We've asked GDAL to cite GRASS 4.1 (CERL) in the header comments, and
I think it would be nice to cite the Horn 1981 paper as well which
contains the original slope algorithm.

Once that is done I'll forward the patch to Matt and request he does
the same and we can all move on.


regards,
Hamish