[GRASS-user] v.surf.idw G_Malloc

[Hamish]

Matthew James wrote:

> I am trying to generate yield maps. I have csv files containing x, y
> and yield columns.
> 
> The yields are calculated at random spots around the paddock.
>
> In general these files can be many thousands of points long.

they can be up to a few million points long before you have to resort
to "tricks".

> When I try to run v.surf.idw I get a “G_Malloc – out of memory error”
> – this occurs almost instantaneously.
> 
> I’m not at all short on resources (have about 2gb of RAM and a huge
> pagefile) and I’m wondering if there is some way around this problem.

I'd guess your region settings are wrong. You have to constrain the IDW
calculation to what you want the raster output map to be like.

try 

g.region vect=PointsMap

to zoom to the extents of your points map. Then

g.region -p

and 

g.region res=[something] -a

to set an appropriate resolution.

Anything larger than 5000x5000 rows x columns (g.region -p) is
beginning to get big for a raster map. (GRASS can deal with bigger
regions than that, but it starts to take a long time + disk space)



Hamish



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