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Ray Arvidson

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  1. You need files of the same size to do New File Builder. Read up on making and using masks to subset another data set. Ray
  2. OK, now I see what you mean. These 1.2 micrometer features could be real absorptions. Smectite clays present such an absorption. Look at the ENVI spectral library that is part of CAT. Given that my job is to help you get to the spectra and interpret without interpreting artifacts, I will leave it to you to do the assignments. Ray
  3. You must join files of the same size, in terms of lines and samples. Subset the larger file using the smaller file to generate a mask of for the smaller size and then use the mask to subset the larger file to fit the size of the smaller file. Then use New File Builder. Read the instructions on doing New File Builder and you will see where you went astray. Rochdi, as before in our many emails, may I suggest that you need to read the documentation before embarking on a new process. Ray
  4. You lost me. Please resend the plots with the features labeled at 1.2 micrometers that you think might be due to mineralogy. Ray
  5. These are spike artifacts in the data. Sometimes the instrument individual detectors are ill behaved and this is an example. Sometimes it is associated with going over sharp albedo boundaries where a detector has memories of what it was just sampling. There are no minerals that I know of that have such narrow single detector absorptions. Please ignore these spikes. Ray
  6. Please attach a spectrum that shows this feature. I strongly suspect that it is an instrument artifact. Include the scene ID from which the spectrum was retrieved. Ray Arvidson PDS Geosciences Node Manager CRISM Science Team Member
  7. No need to run IDL directly. Just launch the New File Builder under Raster Management tool bar to combine the two cubes. Ray
  8. After separately registering the S and L mapped data to the CTX data I would use New File Builder under Raster Management to make an S, L combined mapped cube. Ray
  9. Because the bad bands are applied in CAT using the HDR record and in the spectral display. Remove them manually from the text file using the bad band list in the HDR list.
  10. Bad bands have been applied to TRR3 products. TRR2 products should not be used as they represent only an initial phase of calibration. You can see which bands have been assigned as bad by looking at the ENVI header records. Ray Arvidson
  11. The DDR has elevation data from MOLA observations. In sensor space so just project the DDR using CAT and use the projected MOLA elevation plane. Otherwise no special DEMs for CRISM data. Ray
  12. You cannot do a spectrum from a monochrome image. Overlay the spectral index map over the TRDR data. Then select the TRDR data on the ENVI vertical toolbar and then you can see the spectra for bright areas in the spectral index map, if you move the cursor the the bright pixels in the spectral index map. Ray
  13. Flatten is used to reduced column to column variations in sensor space TRDRs. The TERs have already been flattened. Ray
  14. The best data set to use is the MTRDR, if this product exists for your scene. Next best is the TER, which you can map project using CAT, again if it exists for your scene. Next is the TRDR data set. You have the correct descriptions. Ray Arvidson
  15. Yes, it is normal. You can rename the axis title once the plot is displayed. Ray
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