[GRASS-user] Migrate to Grass 7 question; vector topology?

[Nikos Alexandris]

On Friday 15 of March 2013 17:02:01 Nikos Alexandris wrote:
> On Friday 15 of March 2013 09:31:06 Stephen Sefick wrote:
> > All,
> > I am thinking of moving to grass7.  I know that the vector back end has
> > changed and there is a requirement to rebuild vector topology.
> 
> Better & Faster (thanks to all and especially to Markus Metz) :-)

On the matter,  I just imported the following data set:

402K BurntAreas_2000_2012.dbf
367 BurntAreas_2000_2012.prj
7.9M BurntAreas_2000_2012.shp
115K BurntAreas_2000_2012.shx

# both cases, identical report on overlapping areas:
--%<---
WARNING: 11018 areas represent more (overlapping) features, because
         polygons overlap in input layer(s). Such areas are linked to more
         than 1 row in attribute table. The number of features for those
         areas is stored as category in layer 2
-----------------------------------------------------
14685 input polygons
Total area: 4.78085E+10 (34287 areas)
Overlapping area: 4.05856E+09 (11018 areas)
Area without category: 9.32859E+08 (3744 areas)
--->%--


in G6, revision=55280M

real    2m4.002s
user    1m19.377s
sys     0m9.093s

# v.info -t returns
nodes=63241
points=0
lines=0
boundaries=57140
centroids=30543
areas=34287
islands=9845
faces=0
kernels=0
primitives=87683
map3d=0


in G7, revision=55284M

real    0m33.384s
user    0m29.194s
sys     0m4.092s

# v.info -t returns

nodes=32698
points=0
lines=0
boundaries=57140
centroids=30543
areas=34287
islands=9845
primitives=87683
map3d=0


Much faster!!
Thanks, Nikos

--
ps- Curious: why is the reported number of "nodes" different?
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