🚀 go-pugleaf

mccauley@ecn.purdue.edu (Darrell McCauley) writes:

>I have data (a soil property) on a non-uniform grid for an area of a
>few hectares.  In one direction, the samples are spaced approx. 5-8
>meters apart, but in the other, they are spaced approx 20-30
>centimeters apart.  [I'm using a sensor and a slow-moving vehicle to
>make these measurements. Since the vehicle does not/cannot always travel
>in straight lines, I do not have a regular grid.] As far as I know, 
>no one has ever sampled soil properties this densely.

Scattered data interpolation can be done by a wide variety of methods
For a summary of such methods, ftp
cod.nosc.mil  /pub/grid.ps
              /pub/grid.tex
              /pub/grid.ascii
However, because your data is anisotropically scattered it is likely
that the only method you will find to be satisfactory is natural
neighbor interpolation because this methods uses local subsets of
data which are choosen in a manner that compensates for the
anisotropic density of the data.  If you, or anybody else, would like
a demonstration of this method, send me your most nasty data set and
specify the desired regular grid size.  I will grid the data, either
on a rectangular or triangular grid as you wish, and then you may
display the grid with any conventional contouring package.  If the
grid size that you choose is dense enough, the contouring package
will not alter the representative surface defined by my grid.

This offer implies no obligation on your part or mine.

--
Dave Watson                          Internet: watson@maths.uwa.edu.au
Department of Mathematics            
The University of Western Australia               Tel: (61 9) 380 3359
Nedlands, WA 6009  Australia.                     FAX: (61 9) 380 1028