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Re: 3-dimensional integration? [IDL 5.4] [message #35546 is a reply to message #35545]

Mon, 23 June 2003 06:36

Timm Weitkamp
Messages: 66
Registered: August 2002

Member

Hi Ingo,

Today at 12:37, you wrote:

> I am dealing with 3-dimensional experimental data of x-ray diffraction pole
> figures. I read-in the data, graphical representation (x,y,int) and analysis
> works fine with SURFACE... Now I would very much like to get the volume of
> certain regions of my figure, i.e. circles or squares around a certain point
> (x,y) in order to be able to compare the total intensities of peaks
> belonging together. Could anybody give me a hint with which approach I could
> solve that? Is MESH_VOLUME a senseful idea?

I don't know if this is what you're looking for, but to integrate your
data over a square of (2n+1)^2 pixels around the pixel with the indices
[x,y], just do

tot = TOTAL(data[x-n:x+n, y-n:y+n])

Circular regions take more than one line, but are easily doable too.
Assume that r is the radius of the circle over which you want to
integrate (in pixels). Then you should do something like this:

dim = SIZE(data, /DIMENSIONS) ; Find out size of data array

; Get x and y coordinate for each pixel

xarr = findgen(dim[0]) # (1+fltarr(dim[1]))
yarr = findgen(dim[1]) ## (1+fltarr(dim[0]))

; Get radial coordinate around (x,y) for each pixel

rarr = SQRT((xarr-x)^2 + (yarr-y)^2)

; Find out which pixels are inside a circle r around (x,y)

idxList = WHERE(rarr LE r, npix)

; Integrate over those pixels

IF npix NE 0 THEN tot = TOTAL(data[idxList])

Hope this helps,
Timm

--
Timm Weitkamp <http://people.web.psi.ch/weitkamp>

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[Message index]

		Re: 3-dimensional integration? [IDL 5.4] By: Timm Weitkamp on Wed, 25 June 2003 01:08
		Re: 3-dimensional integration? [IDL 5.4] By: Ingo Salzmann on Tue, 24 June 2003 07:18
		Re: 3-dimensional integration? [IDL 5.4] By: Timm Weitkamp on Mon, 23 June 2003 07:04
		Re: 3-dimensional integration? [IDL 5.4] By: Timm Weitkamp on Mon, 23 June 2003 06:36

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