Hello,

I don't know if you've had any replies to your question yet but here is
my contribution.

s.surf.idw uses inverse distance squared weighting (hence .idw). The
technique is discussed in many introductory texts.

Try:

Burrough, P.A. (1986) Principles of Geographical Information Systems.
Monographs on Soil and Resources Survey No. 12. Oxford: Clarendon Press.

One of the chapters on interpolation includes an account of inverse
distance weighting.

The technique is also discussed in:

Isaaks, E. H. and R. M. Srivastava (1989) An Introduction to Applied 
Geostatistics. New York: Oxford University Press, pp. 259 or
thereabouts.

I hope this helps,

Chris Lloyd
cdl195@soton.ac.uk

Department of Geography,
University of Southampton

> Please can someone tell me the references/papers where I can get more
> details and descriptions on the numerical approximation (weighted
> averaging) interpolation techniques that is used in the command s.surf.idw
> - surface generation from sites data program. This command was written by
> Michael Shapiro of the USACERL.
> 
> Your help is very much appreciated.
> Thanks.
> 
> 
> 
> Norkhair Ibrahim
> Nottingham University
> UK
> 
> 


