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Re: Multi-band sampling strategy [message #72173 is a reply to message #72171]

Wed, 18 August 2010 11:09

penteado
Messages: 866
Registered: February 2018

Senior Member
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On Aug 18, 2:26 pm, JessW <jess.wal...@gmail.com> wrote:
> Hi Max,
>
> Thanks for responding, and sorry about the fuzzy description of what
> I'm doing. Let me try to clarify.
>
> I am tracking the reflectance change of particular pixels across a
> time-series of Landsat data. So for my current stack of 8 Landsat
> scenes spanning April - October, the program returns 8 reflectance
> values for a given pixel address x,y. ENVI_GET_SLICE seemed ideal for
> this task because it can sample a single pixel location through a
> number of bands; however, as I mentioned, it is very slow when it
> loops over a large number of pixels to sample.
>
> ENVI_GET_DATA appears to work on only one band, so it doesn't seem
> quite as suitable for what I'm trying to do. I'll have to investigate
> the use of ENVI_CREATE_ROI; thanks for that suggestion.
>
> Jess

If your image is not too large to fit in memory, it seems that it
might be better to just get the whole image as a 3D array, once, then
take out the subset you want directly, just with indexing. If the
image is too large, but the section you want fits into a small
rectangle, you could retrieve just that region, defined by the max and
min of your indexes, as a 3D array, then pick the points inside it.

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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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