Jumping into the debate, since it raises some fundamental questions in
my eyes;
On 19/04/10 17:46, G. Allegri wrote:
No problem, this is not what I expect. I just expect a user to be able
to import a polygonal layer, without worrying about topology correctness
(clean/build operations), and do spatial operations on it. Obviously the
correctness of results depend on the operation the user is doing (and
it's his problem) but, i.e. a geometrical clip will be always correct, I
think...
The questions here for me are:
- What is the actual error linked to doing operations on non-topological
formats ?
- Why do you absolutely want GRASS to do this ? If all you want to do is
simple geometry operations on spaghetti files, you can easily do this
with most of the available open source viewers / GIS, such as QGIS,
gvSIG, uDIG, etc or even directly with ogr. Why go through the trouble
of using GRASS for that ?
These operations should be quite fast for native vectors with topology.
With "rapidly" I meant: load data, do-the-op, save the results. I'm sure
that the native grass data structures can deal more efficiently then SF
structures.... but often a user prefer to wait a minute more for the
operation to end, then working a minute to have to manage the data
cleaness (more often it takes much more then a minute, and it doesn't
worth it!)
> Yes, although not that rapidly because pseudo-topology needs to be
built first. Polygons do not need to be clean, but then nobody can
guarantee for the results.
Ok, but the user just have to wait and wath the progress bar
completing... that's ok from his perspective :)
I find it a bit suspicious when user comfort is apparently put so much
higher in priority then correctness of results...
Moritz
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