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Re: Multi-band sampling strategy [message #72183 is a reply to message #72174]

Tue, 17 August 2010 23:35

Maxwell Peck
Messages: 61
Registered: February 2010

Member

On Aug 18, 1:10 pm, JessW <jess.wal...@gmail.com> wrote:
> Hi all,
>
> I'm using an IDL script in ENVI to retrieve the values of a multiband
> image at a user-specified number of pixels. The script works as
> intended, but is quite slow; sampling an 8-band image at ~ 38,000
> pixel locations takes
> 52.35 minutes. The issue is the following loop:
>
> FOR i= 0L, nSamplePix - 1 DO BEGIN
> pixValues[i,*] = ENVI_GET_SLICE(fid=fid,line=(index[1,i]-1),$
> pos=bandsSelected,xs=(index[0,i]-1), xe=(index[0,i]-1))
> ENDFOR
>
> If anyone can suggest an alternate, faster sampling strategy--
> preferably one that doesn't include the purchase of a new, faster
> computer--I would be extremely grateful.
>
> Thanks,
>
> Jess

I'm not clear on what you're doing but have you tried envi_get_data
with the dims keyword, or if that is not appropriate maybe creating a
point or polygon ROI (ENVI_CREATE_ROI/ENVI_GET_ROI_DATA)?

Max

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[Message index]

		Re: Multi-band sampling strategy By: Maxwell Peck on Wed, 18 August 2010 14:11
		Re: Multi-band sampling strategy By: JessW on Wed, 18 August 2010 13:58
		Re: Multi-band sampling strategy By: wita on Wed, 18 August 2010 12:46
		Re: Multi-band sampling strategy By: penteado on Wed, 18 August 2010 11:09
		Re: Multi-band sampling strategy By: JessW on Wed, 18 August 2010 10:26
		Re: Multi-band sampling strategy By: Maxwell Peck on Tue, 17 August 2010 23:35
		Re: Multi-band sampling strategy By: JessW on Wed, 25 August 2010 11:13
		Re: Multi-band sampling strategy By: wita on Tue, 31 August 2010 02:08

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