[GRASS-dev] [GRASS GIS] #2045: r.to.vect: use less memory
trac at osgeo.org
Wed Jun 22 09:28:15 PDT 2016
#2045: r.to.vect: use less memory
Reporter: mlennert | Owner: grass-dev@…
Type: enhancement | Status: new
Priority: normal | Milestone: 7.0.5
Component: Raster | Version: svn-trunk
Resolution: | Keywords: r.to.vect
CPU: Unspecified | Platform: Unspecified
Comment (by mlennert):
Replying to [comment:15 mlennert]:
> Replying to [comment:14 mmetz]:
> > Replying to [comment:13 mlennert]:
> > >
> > > Without (i.e. grass70) my machine became unusable for a while and
then the module execution stopped after a bit more than 5 minutes because
of too little memory. With the fix (grass73) it went all the way to 100%
of writing areas (17 minutes on my machine), but then I got an error
"Category index is not up to date".
> > The -v and -b flags are mutually exclusive. The -v flag is disabled
for certain input/flag combinations, but this test was missing. Added in
> Ah, ok. Why is topology necessary for category values ? Is it because
areas are only defined via topological connection between centroids and
> This is a pity for us: if you want to use, for example, i.segment
results both as raster and vector, you need to keep the link between the
two via the segment ids. As attribute table handling '''really''' slows
things down, -vt is the preferred way to create a vector map with
polygons that have the same category as the segment ids in the raster
> > >
> > > However, my colleague's problem was not in the vectorization stage,
but in the topology building stage. I'm currently testing with -vt and
VECTOR_LOW_MEM=1. It's been running for about 1 h. I'll see tomorrow what
the result is...
> > The topology building stage might need a lot of memory. If a lot of
memory is still in use because of a memory leak in the extraction stage,
the topology building stage is more likely to fail because of an out-of-
memory error. There is no guarantee that topology building will succeed,
but the chances for success are higher now that the (hopefully last)
memory leak in the extraction stage has been fixed. If topology building
still fails with an out-of-memory error, try again with the environment
variable GRASS_VECTOR_LOWMEM set.
> I did use GRASS_VECTOR_LOWMEM=1, but the process was stopped. No
explicit memory error, but AFAIK such stopping of a process happens in
case of memory errors:
> Enregistrement des primitives ...
> 63282475 primitives registered
> 397657832 vertices registered
> Construction des surfaces ...
> Processus arrêté
> real 106m12.306s
> user 28m2.664s
> sys 68m42.260s
> Next try will be to use v.build on the vector created by r.to.vect -b...
> export GRASS_VECTOR_LOWMEM=1
> time v.build seg_full
Construction de la topologie pour la carte vectorielle
<seg_full at rtovecttest>...
Enregistrement des primitives ...
63282475 primitives registered
397657832 vertices registered
Construction des surfaces ...
I, therefore, do not have any means to vectorize this file directly in one
piece on my computer. Memory usage goes up steadily through v.build.
I'll try r.to.vect.tiled.
I'll also try to run v.build through valgrind to see if anything shows up.
Ticket URL: <https://trac.osgeo.org/grass/ticket/2045#comment:16>
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