Try r.neighbors function with the mean or medium neighborhood operation, or, if you are working with categorical values, use the 'mode' neighborhood operation. You can combine the result with the original layer using r.patch so only the no-data cells at the borders are filled with the newly created values

You may also have a look at r.fillnulls, which fills in no-data cells using spline interpolation.

Paulo


On Mon 15 Apr 2013 03:06:29 AM CEST, Hanlie Pretorius wrote:
Hi,

I'm working in GRASS 6.4.2, WIndows 7.

I have a raster file that, for various reasons, has shrunk to smaller
than its original size and it now now longer crosses the boundaries of
a vector layer to which I need to assign values from the raster.

So I was wondering how I could 'grow' the raster all along its
non-null edge by  assigning a value to the edge of null cells that is
one cell 'deep'. Ideally the value assigned should be based on the
values of the surrounding non-null cells without affecting the value
of the original non-null cells. I can then repeat this procedure until
the raster exceeds the boundary of the vector layer everywhere.

So I actually want to 'pad' the raster's non-null values based on
themselves.

I have looked at r.grow, r.spread and r.buffer, but none of them seems
to do what I want.

Any ideas?

Thanks
Hanlie


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