[GRASS-user] v.to.rast

patrick s. patrick_gis at gmx.net
Thu Jul 30 01:17:37 PDT 2015


I tested the approach you proposed, but seems to be very slow for large 
datasets: I am processing ~1000.000 points of observation on a 25m-Grid 
across Switzerland, where only few cells have multiple points inside. 
While /v.to.rast/ takes a few minutes for conversion, the combination 
"/v.out.ascii input=pt output=- column=VAL | r.in.xyz input=- z=4 
output=pt method=sum/" has been running for multiple hours and is still 
in progress.

Is there any alternative to run this conversion? I need it to run 
neighborhood analyses as kernel density with population field, i.e. 
/r.neighbors in=pt out=pt_dens -c size=300 meth=sum/. Maybe there is an 
approach to directly use the vector data and avoid conversion- something 
as /v.neighbors meth=sum/?

Thanks for you help,

On 24.07.2015 04:13, Markus Neteler wrote:
> On Thu, Jul 23, 2015 at 11:00 AM, patrick s. <patrick_gis at gmx.net> wrote:
>> Dear all
>> I am puzzled on the behavior of v.to.rast. When several points fall into one
>> gridcell, the raster seems to get one value but not the sum of these. Is
>> there a way to sum these up instead?
> Yes. I have added a related example here:
> http://grass.osgeo.org/grass70/manuals/v.to.rast.html#convert-vector-points-to-raster-with-raster-cell-binning
> (while it does not really fit to that manual page it is expected
> there. Perhaps we need to really enhance v.to.rast to do such a job
> right away).
> Markus

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