[GRASS-user] Spatial Dissolve

[Darren Cope]

On 5/29/07, Leonardo Lami <lami at faunalia.it> wrote:

> > - run v.clean as per CORINE example (v.clean input=wateroriginal
> > output=waterclean tool=rmdupl) in GRASS shell
> > - at this point I noticed that the attribute values are not carried
> > through and I'm left with only "id" and "cat" - why is this, and will
> > it cause problems later on?
> See the output message of v.in.ogr, maybe there is some problems in the
> structure of the input table


Hi Leonardo:

Thanks for the idea.  I had originally thought that the v.in.ogr was
fine, and that the attributes were lost in the v.clean step.  However,
I looked again, and it does appear that only a portion of the
attributes (e.g. the first 137 features) came through during the
v.in.ogr step.  That may potentially be the cause of the problems with
v.clean?  I've attached the output of v.in.ogr, although I don't see
anything that indicated a problem?

---start output of v.in.ogr: ---

v.in.ogr 'dsn=C:/documents and
settings/dcope/desktop/shp/obm_OBMUSER_waterseg_polyne_poly.shp'
output=test -o
A datum name nad83 (North_American_Datum_1983) was specified without
transformation parameters.





Non-interactive mode: the GRASS default for nad83 is
towgs84=0.000,0.000,0.000.



Over-riding projection check.

Proceeding with import...




Layer: obm_OBMUSER_waterseg_polyne_poly




Importing map 1277 features...




-----------------------------------------------------

Building topology ...


Registering lines:    1000
1837 primitives registered


Building areas:



1530 areas built


1496 isles built


Attaching islands:


Attaching centroids:


Topology was built.


Number of nodes     :   1663


Number of primitives:   1837


Number of points    :   0


Number of lines     :   0


Number of boundaries:   1837


Number of centroids :   0


Number of areas     :   1530


Number of isles     :   1496


Number of incorrect boundaries   :   341


Number of areas without centroid :   1530





-----------------------------------------------------




Cleaning polygons, result is not guaranteed!
Building topology ...


Topology was built.


Number of nodes     :   1663


Number of primitives:   1837


Number of points    :   0


Number of lines     :   0


Number of boundaries:   1837


Number of centroids :   0


Number of areas     :   -


Number of isles     :   -





-----------------------------------------------------




Break polygons:


Registering points ... 128830


All points (vertices): 144066


Registered points (unique coordinates): 128830


Points marked for break:  1947


Breaks:     0
Breaks:    13
Breaks:    22
Breaks:    38
Breaks:    41
Breaks:    68
<snip>
Breaks:  1279



-----------------------------------------------------


Remove duplicates:

Duplicates:     0
<snip>
Duplicates:   459





-----------------------------------------------------




Break boundaries:

Intersections:     0
Intersections:     0 (line 637)
Intersections:     0 (line 1243)
Intersections:     0 (line 1875)
Intersections:     0 (line 2119)
Intersections:     0 (line 2398)
Intersections:     0 (line 2623)
Intersections:     0 (line 2859)
Intersections:     0





-----------------------------------------------------




Remove duplicates:

Duplicates:     0





-----------------------------------------------------




Clean boundaries at nodes:

Modifications:     0
<snip>
Modifications:     0





-----------------------------------------------------




Change dangles to lines:

Removed dangles:     0  removed lines:     0
Removed dangles:     0  removed lines:     0





-----------------------------------------------------




Remove bridges:

Removed bridges:     0  removed lines:     0
<snip>
Removed bridges:     0  removed lines:     0





-----------------------------------------------------

Building topology ...


Building areas:



1712 areas built


1421 isles built


Attaching islands:


Topology was built.


Number of nodes     :   1947


Number of primitives:   3116


Number of points    :   0


Number of lines     :   0


Number of boundaries:   3116


Number of centroids :   0


Number of areas     :   1712


Number of isles     :   1421


Number of areas without centroid :   1712





Layer: obm_OBMUSER_waterseg_polyne_poly




-----------------------------------------------------




-----------------------------------------------------

Building topology ...


Registering lines:    1000   2000   3000
3524 primitives registered


Building areas:



1712 areas built


1421 isles built


Attaching islands:


Attaching centroids:


Topology was built.


Number of nodes     :   3233


Number of primitives:   3524


Number of points    :   0


Number of lines     :   0


Number of boundaries:   2238


Number of centroids :   1286


Number of areas     :   1712


Number of isles     :   1421


Number of areas without centroid :   426





-----------------------------------------------------




4 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



1286 input polygons




total area: 1.945637e+008 (1712 areas)




overlapping area: 1.987796e+006 (4 areas)




area without category: 4.105847e+006 (426 areas)

Successfully finished

---end output of v.in.ogr: ---