[GRASS-user] t.rast.mapcalc for interpolate nulls

[Sören Gebbert]

Hi Diana,
you can try t.rast.mapcalc2 for interpolation:

In case A is your space time dataset of choice, then the expression to
interpolate null() cells
in A is:

t.rast.mapcalc2 --v expression="B = if(isnull(A), (A[-1] + A[1])/2.0, A)" base=b


B is the new space time datasets that will have interpolated values at
null() positions (in case there was data in the predecessor and
successor).

Be aware that t.rast.mapcalc2 is highly experimental. You have to
install the PLY Python module to get it to work.


Best regards
Soeren

2014-05-20 16:38 GMT+02:00 Diana Brito <dianisbrito2 at gmail.com>:
> Hi list!
>
> I have a problem with de mannagment of nulls values, i have a termporal
> serie of lst daily (MODIS), i want to interpolate each image in order to
> estimate de values of the nulls cells, I want to get the value of the null
> cell, by averaging the same position in xy but the previous time and the
> next, i don´t have any idea how to indicate the position of the null cell
> neither the way to calculate the average.
>
> Is it possible to do this with t.rast.mapcalc? how? another function?
>
> I,m using grass71
>
> thanks for your help in adnvance
> --
> Diana Marcela Brito Hoyos
> Biologa
> d.brito at javeriana.edu.co
>
>
>
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