[GRASS-user] d.rast.edit does not save edited cells (?)

[Nikos Alexandris]

Very informative mail ;-)

On Sat, 2008-02-23 at 02:42 +0000, Glynn Clements wrote:
> Nikos Alexandris wrote:
> 
> > > > And another question: Is it possible to ad something else besides an
> > > > Aspect map? Use maybe transparencyt and a background command (like with
> > > > r.digit)? What are the limitations?
> > > 
> > > I'm not sure how a background map could work; it would be obscured by
> > > the map being edited.
> > > 
> > > The aspect map feature was only added because it was present in the
> > > original d.rast.edit module which the script replaces. I have no idea
> > > what purpose it serves.
> > 
> > It makes (some) sense for me. I was and still am doing  a lot of visual
> > interpretation (currently upon MODIS imagery).
> > 
> > I need to collect samples for i.smap for example and with MODIS (MOD09,
> > 250m pix.res) this task is a challenge. And I am not only digitising
> > samples from the scratch, but I use also some classes (e.g. Urban) from
> > valid existing land cover maps. Yet, I need to correct the borders for
> > some of these Urban areas.
> > 
> > From this perspective all kinds of "ancillary" data are useful.
> 
> I'm not doubting the utility of a background map, I'm just not sure
> how it would be implemented.

Sorry for my "brilliant ideas"... I have no clue how this could be done.

> 
> > Aspect
> > helped me to identify some flat areas in agricultural zones (it is
> > expected that flat areas have "one" common aspect... no?).
> 
> It depends what you mean by "flat". A common aspect implies zero
> curvature rather than zero gradient. Exactly horizontal areas have an
> undefined aspect (the direction of steepest slope isn't meaningful if
> there is no slope). Areas which are roughly horizontal tend to have
> essentially random aspect.

Hmmm, I see... - depends also on the resolution of the data. Have to be
more careful.

> 
> > It would be
> > even more useful if DEM values (pure numbers) could be visualized (like
> > "add cell values layer") or any kind of values from a thematic map.
> 
> It would be easy enough to add additional information, e.g. numbers. I
> suppose that editing a map displayed as numbers over a background
> of filled rectangles would be feasible, as would the converse.
> 
> But if the both the foreground and background consist of filled
> rectangles, you are only going to be able see one of them.
Yep, it's going to be overfilled.

This is why I got stuck with the "linking of two map displays function".
I wish I could program... I would start right away creating this
tool ;-P

> 
-- 
Nikos Alexandris
.
Department of Remote Sensing & Landscape Information Systems
Faculty of Forestry & Environmental Sciences, Albert-Ludwigs-University Freiburg
.
Tel.  +49 (0) 761 203 3697 / Fax.  +49 (0) 761 203 3701 / Skype: Nikos.Alexandris
.
Address: Tennenbacher str. 4, D-79106 Freiburg i. Br., Germany
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