[GRASS-dev] [GRASS GIS] #3030: v. generalize fails to generalize polygons in a random manner
GRASS GIS
trac at osgeo.org
Mon May 9 12:56:49 PDT 2016
#3030: v. generalize fails to generalize polygons in a random manner
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Reporter: dido | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 7.0.5
Component: Default | Version: 7.0.3
Keywords: | CPU: Unspecified
Platform: Unspecified |
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Trying to generalize Greece shoreline + landmass, polygons fishnet'ed with
cell size of 5000 m. Random polygons are not being generalized while they
should be. If fishnet is made bigger (e.g 50 km cell size), then more non-
generalized polygons are visible.
Input is topologically error-free (no overlaps or gaps in input data).
v.generalize output is as follows:
v.generalize --overwrite input=c100_sea_dis_fish at Greece_UTM
output=c100_sea_G120 method=douglas threshold=120
WARNING: Vector map <c100_sea_G120> already exists and will be overwritten
Copying features...
Building topology for vector map <c100_sea_G120 at Greece_UTM>...
Registering primitives...
105726 primitives registered
832947 vertices registered
Building areas...
36099 areas built
2921 isles built
Attaching islands...
Attaching centroids...
Number of nodes: 36449
Number of primitives: 105726
Number of points: 0
Number of lines: 0
Number of boundaries: 69627
Number of centroids: 36099
Number of areas: 36099
Number of isles: 2921
-----------------------------------------------------
Generalization (douglas)...
Using threshold: 120 meters
WARNING: 1953 boundaries were not modified because modification would
damage topology
WARNING: 1951 lines/boundaries were not modified due to over-
simplification
-----------------------------------------------------
Building topology for vector map <c100_sea_G120 at Greece_UTM>...
Registering primitives...
105726 primitives registered
323843 vertices registered
Building areas...
36099 areas built
2921 isles built
Attaching islands...
Attaching centroids...
Number of nodes: 36449
Number of primitives: 105726
Number of points: 0
Number of lines: 0
Number of boundaries: 69627
Number of centroids: 36099
Number of areas: 36099
Number of isles: 2921
-----------------------------------------------------
v.generalize complete. Number of vertices for selected features reduced
from 796848 to 287744 (36% remaining)
(Mon May 09 22:54:11 2016) Command finished (1 min 42 sec)
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Ticket URL: <https://trac.osgeo.org/grass/ticket/3030>
GRASS GIS <https://grass.osgeo.org>
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