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Re: Normalize image after running FLAASH [message #89021 is a reply to message #89016]

Tue, 15 July 2014 20:28

pthlien
Messages: 1
Registered: July 2014

Junior Member

On Wednesday, July 16, 2014 12:52:55 AM UTC+12, Josh Sixsmith wrote:
> Well your example of CASE isn't a single value for comparing which CASE to evaluate. You've got an entire array ie "b3 le 0".
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> Take a look at the example in the help file:
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> http://www.exelisvis.com/docs/CASE.html
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> It's a single evaluation.
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> As for other parts of your code.
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> You've already retrieved the "number of samples (the ns variable)" and the "number of lines" (nl) from you call to "ENVI_FILE_QUERY", so you can probably leave out the lines where you redefine them.
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> Also, I may be wrong, but "b1*float(b1)/10000 doesn't sound like normalizing your data. A value of 9000 now becomes 8100. It sounds like you just need to apply a scale factor in which case just do "b1 / 10000.0"
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> Back to dealing with your different cases, of "LE 0", "GE 10000" etc, just evaluate the array in a series of complement expressions that account for you different cases.
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> result = (b1 le 0) * 0 + (b1 ge 10000) * 10000 + ((b1 gt 0) and (b1 lt 10000) * (b1 / 10000)
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> That might get you what you're after. It'll use a lot of memory in IDL though. Seeing as you're using ENVI try the 'MATH_DOIT" rountine, and ENVI will tile your data automatically.
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> Hope that helps
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> Josh

Thanks Josh so much. It works after I corrected following your advice and the syntax error I got corrected by br[...]=..., not br(...)=

Lien

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[Message index]

		Normalize image after running FLAASH By: phamlien24 on Sun, 13 July 2014 20:42
		Re: Normalize image after running FLAASH By: Phillip Bitzer on Mon, 14 July 2014 16:00
		Re: Normalize image after running FLAASH By: phamlien24 on Mon, 14 July 2014 22:06
		Re: Normalize image after running FLAASH By: phamlien24 on Tue, 15 July 2014 01:20
		Re: Normalize image after running FLAASH By: Josh Sixsmith on Tue, 15 July 2014 05:52
		Re: Normalize image after running FLAASH By: pthlien on Tue, 15 July 2014 20:28

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