[GRASS-user] v.overlay attribute table problem

[Didrik Pinte]

Stranger,

I've tested the following : create the intersection from layer B to
layer A compared with intersection from layer A to layer B :

CASE 1 : 
v.overlay ainput=mpnetwork atype=area binput=management_polygones
atype=area output=base_cells operator=and


CASE 2 :
v.overlay ainput=management_polygones atype=area binput=mpnetwork
atype=area output=base_cells operator=and


The resulting intersection are different and seems to be uncorrect :

CASE 1 :
GRASS 6.2.0 (ALMERIA):~/Documents/ucl/alert/grass > v.db.select
map=base_cells column=a_cat,b_cat,a_area_tot,b_area_tot where="a_cat=37"
a_cat|b_cat|a_area_tot|b_area_tot
37|10|1000000|15000
37|13|1000000|0
37|1|1000000|0
37|8|1000000|0
37|14|1000000|0
37|11|1000000|1527000


CASE 2 : 
GRASS 6.2.0 (ALMERIA):~/Documents/ucl/alert/grass > v.db.select
map=base_cells column=a_cat,b_cat,a_area_tot,b_area_tot where="b_cat=37"
a_cat|b_cat|a_area_tot|b_area_tot

... this is a very strange behaviour ... the CASE 1 gives the correct
intersection and not the CASE2 ...

Didrik

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