[GRASS-user] grass vector model, cats and layers concept

Vincent Bain bain at toraval.fr
Mon Apr 22 07:38:07 PDT 2013

Le lundi 22 avril 2013 à 14:58 +0200, Moritz Lennert a écrit :
> On 22/04/13 14:41, Vincent Bain wrote:
> > Thank you Moritz,
> >
> >> - I'm not sure I like the difference in size of cat values between
> >> layers. It gives the idea that there is one important and two secondary
> >> layers.
> >
> > Sorry, I don't understand. Cats values are all the same font size in the
> > drawing (I turned "1" values to sth else, perhaps an optical illusion)
> Sorry, I was confused by your "id". I'm not sure that this id is helpful 
> in your drawing as most users will never be confronted to id's, only to 
> cat values. I think making them this prominent in the drawing might 
> cause more confusion than help in understanding.

I agree with you that most users won't feel concerned by the feature-id,
especially the majority of people working on imported data (what's more
for the user, there's no way to manage this internal numbering). Those
who learn grass in order to /produce/ geographical data may very soon in
their learning process be concerned by this. My humble opinion is that
awareness of the existence of a geometrical identifier is an integral
part of the problem. I would keep it in the sketch, perhaps as you
suggest in a less prominent appearance.

> No, what I meant is to have a unique cat for each plot in layer 2 and 
> then have an attibute table with columns cat and type, the second then 
> giving the type of the plot, while the first is a unique identifier of 
> each plot.

OK, I'll have a look.


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