[GRASS-dev] GRASS digitizing;
splitting lines does not update the cat!
radim.blazek at gmail.com
Tue Sep 26 10:37:29 EDT 2006
It should be probably a new tool with a new button in toolbox.
On 9/26/06, Stephan Holl <holl at gdf-hannover.de> wrote:
> Hello Maciej,
> On Mon, 25 Sep 2006 17:22:54 +0200 Maciej Sieczka <tutey at o2.pl> wrote:
> > Stephan Holl wrote:
> > > while working with a very long digitized coastline I encountered the
> > > following problem.
> > >
> > > I split the line into pieces in order to give different attributes
> > > to different line segments.
> > > But when I split the line, the cat stays identical. So whenever I
> > > change an attribute of one segment, it gets changed on all other
> > > segments too (because it has the same cat).
> > >
> > > This is because no new attribute-entry will be created when a line
> > > is split and the cat stays identical.
> > >
> > > Would this be a big deal to change this? Where is the right place to
> > > look at?
> > >
> > > My needed behaviour would be that when splitting a line, the
> > > attribute-entry gets copied, the new resulting segment gets a new
> > > cat linked to the copied entry. The left-of-new-point-segment stays
> > > old, the right-of-new-point-segment gets the new cat linked to the
> > > new cat.
> > >
> > > What do other think? Is this a convnient usecase?
> > The functionlityyou are describing would be very usefull for me as an
> > option. But the current behaviour should also be still available - it
> > has it's own uses.
> Yes, you are right.
> > Currently you can remove the old cat and add a new one, then fill the
> > attribute table again. This becomes a problem, when you have, say, 100
> > attributes but only wan't one to be different :(.
> If someone could point to the place in the sources where to start I
> would like to try what I can do.
> AFAIK the following steps need to be done.
> 1) finding the funtion, which does the spliting
> 2) get maximal category number from db
> 3) select values from database
> 4) assign new cat to new line-part
> 4) store copy of the values to database table with new category number
> > > Could this be done with GRASS/QGIS right now?
> > AFAIK same as above. I would love to see such a functionality in QGIS
> > Grass edit tool, too.
> Yes, thats the place I like to have it too!!
> Best regards
> GDF Hannover - Solutions for spatial data analysis and remote sensing
> Hannover Office - Mengendamm 16d - D-30177 Hannover
> Internet: www.gdf-hannover.de - Email: holl at gdf-hannover.de
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