Missing Values

I have a field where some of the values are NaN.
I would like to remove these missing values by changing them
to their nearest neighbor (or some other algorithm).
Is there a visad way of doing this? 
Or do I have to define some sort of custom interpolation?

Thanks


Cameron Shepherdley <C.Shepherdley@xxxxxxxxxx>
AutoTAF Project Developer 
Bureau of Meteorology, Melbourne, VIC 3001, Australia
Telephone: +613 9669 4652