v. generalize fails to generalize polygons in a random manner
— at Version 5
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@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@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@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)
Added attachments with generalized data over the original data, where the non-generalized polygons are well-visible.
Dataset can be provided upon request. GRASS version is 7.0.4 (missing in the list). How can I modify the description -- looks ugly after I pasted the GRASS output :-)