| 10 May 2012 10:15 PM |
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Hi,
I'm trying to read spectral signature from my Hydrothermal RGB (tool-profile-z profile). Its giving value X- axis band number and on Y- axis value (0.8 to1.8) . The graph is showing almost same pattern everywhere on image (using ETM+). plz help me to read (collect) correct value and method.
Thanks
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Deleted User
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| 11 May 2012 04:11 AM |
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Thanks art23130 but I'm new ENVI user Can u pls explain step by step?
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Deleted User
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| 11 May 2012 06:26 AM |
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Thanks art23130, I tried in IDL graph open but I'm unable to process it their as it is very new env to me. Kindly explain me any simple method how to match my Z- profile curve with spectral library.
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| 11 May 2012 07:10 AM |
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Thanks a lot art123130, I'm following this tutorial only but not able to find mineral as I dont have any geological info regarding this area. In this tutorial they already specified what is pixel point mineral you need to enter value n match spectra. But i'm unaware what is mineral. kindly suggest me how to know which mineral feature is that particular pixel point.
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| 11 May 2012 08:18 AM |
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Is you ultimate goal to identify the materials in your scene? Or maybe to find specific materials of interest? Your original question makes me wonder whether you've converted the raw ETM+ data to radiance and then atmospherically corrected it? You would need to do those things before your image pixel Z profiles will look like reflectance spectra. ENVI has a tool under Basic Tools > Preprocessing > Calibration Utilities > Landsat Calibration that you can use to convert the raw data to radiance. Then the most common way to atmospherically correct it would be using FLAASH, which is part of ENVI's atmospheric correction module. Do you have that module?
Once the data have been converted to reflectance, then you can compare pixel spectra to library spectra (if there is a library that contains spectra for the materials in your scene), using a tool in ENVI that is found under Spectral > Spectral Analyst.
I highly recommend reading the documentation for all of these tools before you use any of them.
- Peg
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Deleted User
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| 11 May 2012 08:23 AM |
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Thank you art23130, for your invaluable guidance I'll defiantly try it out however I may need to trouble you little bit more in case I have some doubt.
rgds
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| 11 May 2012 08:42 AM |
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Thanks Peg, I have converted my data into radiance and then I used QAC as I do not know how to find out lat- long- elevation and pixel size values for ETM+ .txt file . My major aim is to find out the materials in the scene. Only after that I can go for particular material.
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