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adel.naseri

Why my result of flaash useing aster data is incorrect?

16 posts in this topic

when i rectify spectral profile of my result image to original image, the curves is perfectly  different.

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could you post the screenshoot please

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the right image is corrected image and the left on is the original image.

in this three pictures i compared the spectral profiles of two images in Three different locations.

jp3b_1.jpg

 

38x6_2.jpg

ue7r_3.jpg

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1. evidentemente las firmas espectral de ND y reflectancia (FLAASH) deben ser diferentes.

2.Factor de escala es 10.

3.Coloca la firma espectral de la vegetacion y comparalo con el teorico.

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thanks "peralta2794"...

1.I do not think that the differences in spectral profiles of one location in both images is evident. it is possible they have Small differences But not like this Big differences.

2.The scale factor is 10.

3.The area covered by my image is desert therefore doesn't have vegetation or water bodies.

 

 
 

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thanks "Arhanghelul "....

I did not downloaded this image by myself but my professor gave it to me...

 
Most likely he downloaded it from USGS.

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Dear Cadet,

 

As FLAASH module multiplies the output (surface reflectance data) by 10,000 omitting decimals for faster calculations and lower file size, we should apply this equation:

 

(B1 le 0)*0+(B1 ge 10000)*1+(B1 gt 0 and B1 lt 10000)*float (b1)/10000

 

where;          

le  means less than or equal          

ge means greater than or equal          

gt  means greater than         

lt   means less than

 

The resulting surface reflectance data will lie between 0 to less than unity (0 to <1) suitable for further image spectrometry and comparable with most spectral libraries.

 

I hope that helps

 

Regards

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Dear Cadet,

 

As FLAASH module multiplies the output (surface reflectance data) by 10,000 omitting decimals for faster calculations and lower file size, we should apply this equation:

 

(B1 le 0)*0+(B1 ge 10000)*1+(B1 gt 0 and B1 lt 10000)*float (b1)/10000

 

where;          

le  means less than or equal          

ge means greater than or equal          

gt  means greater than         

lt   means less than

 

The resulting surface reflectance data will lie between 0 to less than unity (0 to <1) suitable for further image spectrometry and comparable with most spectral libraries.

 

I hope that helps

 

Regards

Yes..You have to scale your data using this eq

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Thank you so much my friends....my problem is solved...i applied above equation.





 







Thanks again







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Dear Adel.naseri,

 

You much welcome. Do you mind sharing your methodology for UHI retrieval using Aster data.

 

thank you

 

Regards

 Achoknyz 

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I do not mind uses aster data for retrieval of UHI. I'm using this data for mineral mapping...Sorry

 

 

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Dear Adel.naseri,

 

You much welcome. Do you mind sharing your methodology for UHI retrieval using Aster data.

 

thank you

 

Regards

 Achoknyz 

Maybe he just use LST?

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Si existe vegetacion, la tonalidad roja es vegetacion, puedes poner el cursos en esa zona roja y mostrar su firma espectral, ademas no tiene logica (-20000, 30000) en out-ref... el rango de la reflectancia usando FLAASH es (0, 10000).

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