[GRASSLIST:7381] Re: v.digit in 6.0

Maciek Sieczka werchowyna at epf.pl
Wed Jun 29 15:58:35 EDT 2005

From: "Hamish" <hamish_nospam at yahoo.com>

>> > I am trying to do something with v.digit in new grass and I found
>> > that it is totally useless (or I miss something). It seems to be
>> > impossible to pan screen without ending digitizing the line!
> ..
>> That's right, v.digit is of not much use in it's actual form. The
>> issue you mention is not the only problem. This has been discussed a
>> bit in both grasslist and grass-devel.
> It works just fine for points and cleaning up topology. I think "not
> easy to use for your task" is a more accurate representation. If you
> want to pan, you have to end the line, pan, draw another, and then snap
> the two together apparently. A pain, but possible.
>> Also check the bugtracker for other complaints on v.digit.
> Note that a lot of those will be for v.digit from GRASS 5, an entirely
> different program.

Right. I should have pointed to particular reports.

>> v.digit needs a volunteer who'd fix it. Nobody by now.
> Correct; but again, I would say "improve" rather than "fix". For many
> tasks it is fully adequate.

I don't agree that "improve" is a better word, because v.digit suffers from 
two serious bugs:

Zooming in v.digit changes resolution in region settings:

Big bug I think. I can't see how it is possible to accurately digitize, even 
points, when your backdrop raster map gets resampled and displayed 
differently each time you zoom in or out?

(My bugtracker entry is poor here. Please ignore the note about changing the 
res to a half of it; actually I learned that v.digit changes the resolution 
much more freely).

If you zoom in/out much v.digit is likely to crash:

Which happened to me many times *exactly* when I was manualy fixing 
topology. Imagine how badly I was dissapointed when my work gone with the 
wind for the first time. Then I got used to quiting v.digit from time to 
time, doing backup and g.region to set a reasonable res (it seems that this 
crash is connected with the resolution changing by v.digit; maybe when res 
gets to fine v.digit cannot handle it anymore?) and going back to v.digit. 
That's very time-ineffective.

I guess that http://intevation.de/rt/webrt?serial_num=3164&display=History 
refers to the same problem.

Having said it all I conclude v.digit needs fixing, not improving or 
extending it's capabilities. Which is easy to say and harder to do when only 
few comitted coders work on Grass, I know. I'm writing this only to clear 
the things out hopefully, no offence by any means.

>> However there's QGIS which has a very nice plugin for digitizing Grass
>> layers,
> Correct.

If not the QGIS, none digitizing or vectors editing would be possible in 
GRASS (for me at least).


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