[GRASS5] v.support/v.build

[Radim Blazek]

On Thursday 18 April 2002 04:57 pm, Michel Wurtz wrote:
> Look at http://pages.infinit.net/danmo/e00/index.html
> Daniel has a good analysis of it

Thanks, good.

>> If you have threshold for e00, what that means?

> The values used for pruning lines 

If pruned by Arc/Info, no need to use thresh by v.support

> and for the ESRI equivalent
> of v.support (the values may not be the same)

In v.support threshold is used for building clean topology
from incorrect linework. Unfortunately, it may also build
incorrect topology from clean data.

>> If it means that the file contains unclosed areas with
>> gaps < thresh and does not contain lines with vertices
>> in distance < thresh it is of course best to use that.

Sorry, here i was not precise. Distance of vertices of one line
may be smaller than threshold, but topology formed by first
point outside the threshold must be also OK, i.e. line between 
first point and first point outside threshold should not cross
the neighbour line. I know, it is not too clear explanation.

> If topological information is present, the topology is clean
> (there is no gap : vertices are connected)

Then threshold should not be needed for v.support.

Radim