[GRASSLIST:4036] Re: topological snap across layers

[Radim Blazek]

On Tuesday 27 July 2004 12:49, Leonardo wrote:
> Hi,
> I'd like to know if Grass is capable to make snap across layers.
> I try to explane me.
> I'd like to digitilize a vector that has part of its boundary coincident
> with linear or boundary components of an other vector.
> It will be useful if, when I digitilige the boundary of the new vector
> along the boundary of the second vector that is in background, the result
> is that the two parts of the two vector are topolological coincident.
>
> Is possible make it?

1) No, currently it is not possible. It is however QGIS/v.digit feature,
it does not depend on the GRASS library but on the editor implementation.

2) GRASS can mix more 'layers' in one 'vector'. GRASS vectors are suitable
for complex data models in which more features from different layers
share the same geometry. An example is the vector 'multi' from 5.7 demo dataset.
Of course, it is not always possible, but it should be considered, 
if the two layers cannot be combined into one vector. 
Tell us more details about your data.

Radim