[GRASS-dev] lib/vask

[Glynn Clements]

Michael Barton wrote:

> It would probably be a good idea to also fold in i.ortho.photo if it is not
> too difficult.
> 
> Glynn has recommended using the GDAL library for rectification. Could we
> fold all raster rectification--general purpose and aerial photo--into
> i.rectify with appropriate options and flags? If so, we could add the
> additional rectification methods Hamish mentioned in an earlier post.

The rectification aspects of i.orpho.photo should probably remain
separate. AFAIK, it's completely different to the other rectification
methods.

> >>> various [Confirm][Cancel] buttons are needed...
> >> 
> >> In most cases, it's preferable to execute operations without
> >> confirmation and to provide an undo feature for dealing with mistakes.
> > 
> > Undo is definitely the way to go here.
> 
> I'm not sure what undo would mean for georectification. For GRASS, you
> always create a new map with georectification. The original, unrectified,
> map remains as it was. Same with the GCP file. So undo is kind of
> meaningless. Same with confirm and cancel. If the new map doesn't look
> right, just delete it, change the existing GCP's, applying them to original
> map, and do it again.

My guess is that the confirm/cancel thing is an artifact of using a
Vask/XDRIVER GUI, where the application decides what the user can
change and when. So if the user makes a mistake, the application has
to offer them the option of and correcting it (re-starting the whole
process form scratch isn't a sensible option).

With a "real" (i.e. event-driven) UI, the user can normally change
anything at any time. An undo option may still make sense; e.g. if you
accidentally delete a GCP which took some time to place accurately,
being able to press an undo button is preferable to having to do it
all over again.

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