[GRASS-dev] lib/vask

[Glynn Clements]

Michael Barton wrote:

> What is needed is a predictable place to put GCP files--for RMS calculations
> (i.e., projected xy or distance between projected xy and specified e/n for
> that point) and for rectification.

Or you could just use a filename rather than assuming a specific
location within the mapset directory.

> I'm assuming that you'd need all the GCP's to do the forward projection of
> GCP's. What form would you want to return them in?

Sorry, I don't understand the question.

> I think the only things that goes into a $GISBASE/group/[mapname] folder are
> a POINTS file with GCP's and a REF file with a list of raster maps to be
> rectified with the POINTS file in the directory. Any suggestions for a
> location if not $GISBASE/group? If we move the GCP's then i.rectify will
> have to be changed or an r.rectify will have to be created to read GCP's
> from the new location.

The most straightforward option is a separate directory, with
arbitrary filenames. Any operation using GCPs would need to take the
name of the GCP file as an option (e.g. "i.rectify ... gcp=...").

An extension would be to create a file in the cell_misc/<mapname>
directory containing the name of a GCP file and the projection details
of the target coordinate system used by that file. This would allow
you to rectify an image into any location.

-- 
Glynn Clements <glynn at gclements.plus.com>