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Trying to address this SE question:
I tried to apply v.generalize to a subset of area features, using a where clause, but it doesn't seem to be working. All features are generlized, as if the where clause is being ignored. Here's an example from the nc_basic_sm MAPSET:
micha@TP480:~$ v.extract geology output=my_geology --o
where="GEO_NAME='Qp'" .....
micha@TP480:~$ v.db.addcolumn my_geology column="area_sqkm DOUBLE" micha@TP480:~$ v.to.db my_geology option=area
column=area_sqkm unit=kilometer
# Only 21 features are larger than 10 sq.km.: micha@TP480:~$ v.db.select -c my_geology column=area_sqkm
where="area_sqkm>10" | wc -l
micha@TP480:~$ v.generalize my_geology output=my_geology_smooth type=area method=douglas thresh=100 where="area_sqkm>10" --o .... v.generalize complete. Number of vertices for selected
features reduced
Now viewing both my_geology and my_geology_smooth shows that
*all* features were smoothed. Including those island polygons that
were much smaller than 10 sq.km.
Am I missing something?
-- Micha Silver Ben Gurion Univ. Sde Boker, Remote Sensing Lab cell: +972-523-665918 |
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