[GRASS-user] r.region question

[Rich Shepard]

On Thu, 16 Aug 2018, Moritz Lennert wrote:

> When working with the raster approach to geographical data, the user has
> to make a (more or less arbitrary) choice on the extent of the zone he
> wishes to work on and on the resolution within that zone. This is what
> g.region allows you to do: it defines the raster grid in which raster
> operations will take place. If your original data does not correspond to
> this grid it will be clipped and resampled to the grids definition.
>
> r.region allows you to redefine the intrinsic characteristics of your
> data. Where g.region defines the grid you want to use for operations,
> r.region allows you to modify the definition of the grid of a particular
> raster map (and it will then be saved in that new definition). This is
> useful, for example, when certain data providers define the cell location
> differently (top left corner of the cell, center of the cell, etc), and
> you have to adapt the data to GRASS' definition. So r.region is useful to
> "correct" a specific raster map's definitions.

Moritz,

   This is a really useful explanation and I appreciate finally learning of
these differences. When I'm able to write to the wiki I can add this
information to an existing or new page.

> v.region does not exist.

   I forgot this.

> The current parameter names are consistent, but you might argue whether
> the solution is the best: "map" is used for modules where one map is
> handled and no output maps are created (r.region is one such example, but
> also v.info, etc). "input" is used for modules which also create "output".

   This distinction also is new to me. It makes sense yet I've not before
been aware of it. When is "name" the preferred choice?

> Personally, I have no fundamental objection to replace all "map"
> parameters with "input", but this would have to be discussed widely on the
> mailing lists.

   +1

Regards,

Rich