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Last Post 19 Aug 2016 01:06 PM by  anon
computing ndvi for every pixel in the satellite picture (landsat 8)
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anon



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19 Aug 2016 01:06 PM
    Hi Using envi, I generated .dat file that contains radiometric calibrations. Then using spectral tab then vegetation I generated NDVI file. My problem now I am not able to read the ndvi file so I can used every read value to calculate emissivity(I have the equation based on NDVI value for each pixel) for each pixel. Could you please help me.

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    22 Aug 2016 06:55 AM
    I do not understand exactly what the problem is. Perhaps you can clarify? Is the problem that you cannot read back into another ENVI session the NDVI image that you made in another ENVI session? Or is the problem that you do not know how to apply the equation that you have for emissivity? If the problem is understanding how to apply your equation, it may help if you can tell us what the equation is. Regards, Peg

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    22 Aug 2016 01:05 PM
    Thanks for your reply: The problem that I do not know how to apply the equation that I have for emissivity? More explanation: Like I said before, I generated NDVI file, the next step I want to apply my equation. In other words I have to read NDVI file pixel by pixel as I guess and depending on NDVI value of that pixel I have different equation to be applied. The emissivity equation should be applied to every pixel of the image. you can find the equation in: http://www.umbc.edu/rssip...GARS.LandSurface.pdf it is in page 318, equation (8), ndvis is 0.2, ndviv is 0.5 Thanks

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    23 Aug 2016 11:25 AM
    In general, you can apply equations like this in ENVI using Band Math. See the docs for Band Math here: http://www.harrisgeospati...BandMath.html#Enter. You will need to use conditional operators ("gt" for greater than, etc.) to determine which pixels meet which criteria for one equation. If you need to use several lines of IDL code to get the whole algorithm implemented, you can form that into an IDL function. If you then put that function into your ENVI or IDL path (for example, by putting it in the ENVI save_add directory), IDL will restore it when ENVI starts. It will then be available for you to call as part of your Band Math expression. Regards, Peg

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    23 Aug 2016 11:55 AM
    Thank you very much I appreciate your help. I will work on it, and let you know
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