G. Allegri ha scritto:
Thanks for the ideas.
I've just tried Starspan but it's performance is still too slow. I've
let it run for 15 minutes...
r.statistics is probably the best solution. I've investigated the
ArcGIS method and it actually seems to use a similar method
(ratserization of the features and various automations to join the
results). In fact they call the module "zonal statistics" that is
generally a set of raster basded methods.
the only limitation of the actual r.statistics is that it works only
with CELL and not float. Ok, I can multiply my values and convert to
CELL, but we could try to let r.statistics deal with floats too...
see flags on r.statistics:
-c Cover values extracted from the category labels of the cover map
Setting the -c flag the category lables of the covering raster layer
will be used. This is nice to avoid the GRASS limitation to interger in
raster maps because using category values floating point numbers can be
stored. [1]
[1] http://grass.itc.it/grass63/manuals/html63_user/r.statistics.html
Ciao,
giovanni
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