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Re: mapping/interpolation from one irregular grid to another (different) irregular grid. [message #79019 is a reply to message #79007]

Tue, 24 January 2012 23:38

Dick Jackson
Messages: 347
Registered: August 1998

Senior Member

Hi Paul,

If I understand you right, I'd say GridData is at least worth a try. Online help has several examples, but none doing quite what you want. Using the variables from there (scattered points f as a function of x and y):

; Create a dataset of N points.
n = 100 ;# of scattered points
seed = -121147L ;For consistency
x = RANDOMU(seed, n)
y = RANDOMU(seed, n)

; Create a dependent variable in the form a function of (x,y)
; with peaks & valleys.
f = 3 * EXP(-((9*x-2)^2 + (7-9*y)^2)/4) + $
3 * EXP(-((9*x+1)^2)/49 - (1-0.9*y)) + $
2 * EXP(-((9*x-7)^2 + (6-9*y)^2)/4) - $
EXP(-(9*x-4)^2 - (2-9*y)^2)

; -----
; Then, create another set of irregular (x, y)
; points to sample, and sample them:

xOut = RandomU(seed, n)
yOut = RandomU(seed, n)
fOut = GRIDDATA(x, y, f, XOut=xOut, YOut=yOut)

; -----
; To confirm that the gridding of this small set of points is
; doing what we intend, these two contour plots bear some similarity:

!P.Multi=[0,1,2]
Contour, f, x, y, /IRREGULAR, LEVEL=FIndGen(11)/10*5, /FOLLOW
Contour, fOut, xOut, yOut, /IRREGULAR, LEVEL=FIndGen(11)/10*5, /FOLLOW

There are loads of options in GridData for interpolation methods, etc.

Hope this is helpful in some way.

Cheers,
-Dick

Dick Jackson Software Consulting
Victoria, BC, Canada
www.d-jackson.com

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[Message index]

		Re: mapping/interpolation from one irregular grid to another (different) irregular grid. By: Maarten[1] on Thu, 26 January 2012 01:30
		Re: mapping/interpolation from one irregular grid to another (different) irregular grid. By: Dick Jackson on Tue, 24 January 2012 23:38
		Re: mapping/interpolation from one irregular grid to another (different) irregular grid. By: Klemen on Tue, 24 January 2012 15:54
		Re: mapping/interpolation from one irregular grid to another (different) irregular grid. By: David Fanning on Tue, 24 January 2012 14:21
		Re: mapping/interpolation from one irregular grid to another (different) irregular grid. By: Paul Van Delst[1] on Thu, 26 January 2012 08:53

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