Ray Arvidson
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Posts posted by Ray Arvidson
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Hi Emran:
I am a CRISM Science Team Member and PDS Geosciences Node Manager. . With regard to processing CRISM data there is no need to convert from radiance to I/F files for the TRDRs because there are already I/F file versions of the TRDRs that have been cleaned up for noise. Use those I/F files. These have values of radiance detected by CRISM divided by the solar radiance at the heliocentric distance for the time of the observation. CAT at this time only has a volcano scan atmospheric correction. It is under ATP correction. I usually check photometric correction on and the program divides by the cosine of the incidence angle, this makes it a Lambert albedo. The display error message sometimes appears in ENVI classic and 5.4. Feng can talk you through it. Let me now what you are trying to get from the CRISM data and I can help walk you through what I would do to try and get there. Pretty complicated data sets and it is easy to get lost in them and become a bit frustrated. I look forward to hearing from you.
Ray Arvidson
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Attached are some slides showing how I used ENVI to ingest M3 lunar data and lab data, resample the lab data to the M3 wavelengths, and overplot the two data sets.
Ray Arvidson
PDS Geosciences Node Manager
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Here to help. I am not sure why you have a screen shot of a vertical profile, which suggests to me you opened the spectral library as an image. To examine the spectral library data you need to open the file as a spectral library, not as an image. Did you open it as a spectral library, and could you display spectra? If you did this and can display spectra, resampled to M3 bandpasses, you should be able to overlay spectra from an M3 cube pixel with the lab spectra. Let me know what you did and I can help more if the instructions above are not enough. Worst case is for me to try what you wanted to do with the exact data sets you used.
Ray Arvidson
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Greetings:
You can use both the new ENVI5 series interfaces or the Classic ENVI interface to a resample spectral data set to a new set of center wavelengths and, optionally, band passes. You will find the spectral resampling procedure under the toolbox on the right hand side of the ENVI5 series interface, and under the spectral heading on the pull down Classic menu. Next select an input data file (it needs to have wavelengths in the header record) that you designate as the new wavelengths for the spectrally resampled data. The dialog box then asks you for the output file that will be resampled. If there are band passes (like Gaussians) in the input data file header these will also be used in resampling the output data set. I just tried it with an OMEGA L data set as the input and one of the ENVI JHU spectral libraries as an example and it worked. It resampled the JHU data to the OMEGA wavelengths and made a new JHU spectral library. Also works with spectral cubes as input and output data sets, etc. Let me know if you still have some problems and we can talk on the phone.
Ray Arvidson
PDS Geosciences Ndoe Manager.
11/6/17
CRISM DATA PROCESSING: CRISM Ratioed I/F Corrected Spectra
in For data users
Posted
Hi There. You are doing the processing correctly. The reason that the map projected plot looks different relative to the before projected plot is that the map projected plot has its scale enlarged. It does look like these plots have been made using Classic ENVI and CAT rather than the ENVI5.3 interface and CAT. I so I recommend you switch to the ENVI5.3 interface, much more powerful than the Classic interface.
Ray Arvidson
CRISM Science Team Member and PDS Geosciences Node Manager