[GRASS-user] Interpolation with v.surf.rst

[Hamish]

Martin wrote:
> > * if input is 2D and zcolumn is not given -> using categories
Moritz wrote:
> I'm pretty sure that this will create lots of confusion. I
> think in this case it should fail with an error message.

Hi,

I tend to agree, even if it is the current situation.

I'm all for making the module interfaces more consise, and
having the program do as much work as possible instead of
offloading job that onto the user in 50 tunable parameters, but
I think it is important to consider that functionality which
changes meaning depending on context is always quite dangerous
and can make the software less intuitve to use.  i.e. it
shouldn't be _overly_ helpful and end up silently doing an
unexpected thing if you forgot to specify an option- in this case
the column, it should throw an error. In the long run that's
more helpful to the user; make sure it gives them what they expect.
I suspect that column=cat would fail in a case when there was
no DB attached, perhaps the hack-around is to check for that
and bypass the db stuff if column=cat is given?

I'm trying to think of times I've used v.surf.rst with column=cat,
and the only ones I can think of is in simple examples where I
just wanted any variable with a gradient in it. Come to think
of it, any interger (categorical) to v.surf.rst input has been
pretty rare.


2c,
Hamish