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Ray Arvidson

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Everything posted by Ray Arvidson

  1. 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.
  2. 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
  3. 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
  4. 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
  5. Flatten is used to reduced column to column variations in sensor space TRDRs. The TERs have already been flattened. Ray
  6. 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
  7. Yes, it is normal. You can rename the axis title once the plot is displayed. Ray
  8. Hi: If you use the data that have IF in their label then no need to convert from radiance to IF. This has already been done for you. The files with RAD in their names do need to be converted. Use the IF files, please. When we developed the archives we wanted to supply an IF file and a RAD file for a given scene. The IF file has been converted from radiance to I/F and denoised. The RAD files have just been converted from raw data to radiance values. Please read the Software Interface Specification Document (https://pds-geosciences.wustl.edu/mro/mro-m-crism-2-edr-v1/mrocr_0001/document/crism_dpsis.pdf) for details. Ray Arvidson Node Manager and CRISM Team Member.
  9. Hi There: I am the Geosciences Node Manager and also a CRISM Science Team Member. I can answer your questions. I/F is defined as the radiance on sensor divided by the solar radiance at the top of the atmosphere that would have occurred during the observation. The TRDRs are presented with these units. It is a form of reflectance but one that has the atmosphere and surface terms included. The Viviano-Beck spectral parameters operate on these data sets. They do not operate on he MTRDRs, which have been processed to remove atmospheric effects and normalized to surface reflectance, with S and L bands joined. This document explains the processing and is a must for reading if you wish to use CRISM data: https://pds-geosciences.wustl.edu/mro/mro-m-crism-2-edr-v1/mrocr_0001/document/crism_dpsis.pdf Ray Arvidson
  10. Hi Maeve: Email me at arvidson@wustl.edu and I will send the Zoom invitation for Monday CDT 3pm. Ray
  11. Maeve: I am in the Central Daylight Savings time zone (CDT). What is your time zone? I am thinking about a one hour Zoom session this Friday at 3 PM CDT. Tell me which MTRDR you would like me to load up for the session on how to do some analyses using ENVI. Ray
  12. Hi Maeve: I would be happy to help out. In the past something like a one hour zoom session worked to get other users familiar enough with CRISM data to get them up and running on analysis. Let me know if this would be a good approach and when you might be available next week. Ray
  13. Maeve: You can load MTRDRs directly into ENVI without the need for the CAT extension. This is because these files come with an envi header. Let me know if this works for you. Ray Arvidson
  14. Maeve: You are downloading CAT from our Geosciences Node site? Try incorporating it into ENVI 5.5.3 or 5.6, not the Classic version. If you need help let me know. We can then go from there. Tryi using our PDS Mars Orbital Data Explorer to find and download some MTRDR files. I can help you get started on how to use the data once you get CAT working with ENVI. Ray Arvidson
  15. Hi Maeve: ENVI is the main way that researchers process CRISM data, including mapping mineral parameter maps. Do you have access to ENVI? And do you know which CRISM scenes you would like to use? I can tutor you through using ENVI and CRISM data, but first let me know if you have access to ENVI software. Ray Arvidson Geosciences Node Manager and CRISM Team Member.
  16. See attached paper, Section 5.3, for what we do for thresholds for parameter maps. Choosing a neutral spectrum is a case of trial and error. I do not do this, rather I just look at the volcano scanned spectra for features such as the 2.3 um metal-OH absorption. Ray Arvidson Viviano-Beck_et_al-2014-Journal_of_Geophysical_Research__Planets.pdf
  17. DISORT is a generally applicable radiative transfer program and is available over the internet. We use a front end that is Mars specific. It is incredibly complicated and not meant for distribution. May I suggest that unless you wish to do Hapke-related nonlinear modeling of mineral grain sizes and phases you just stick to what CAT offers. Except for our group very few researchers try and use DISORT in their CRISM data analysis. Ray Arvidson CRISM Team Member PDS Geosciences Node Manager
  18. The attached paper will show you how the library was created. Ray Arvidson Viviano-Beck_et_al-2014-Journal_of_Geophysical_Research__Planets.pdf
  19. Rochdi: Glad to have helped you along. Stay safe and healthy. Ray Arvidson
  20. Rochdi: I am not sure what you are asking. CAT has spectral parameters for IR data. Use this function. I am not trying to be judgmental. However, I suggest that you need to read in detail the Viviano-Beck paper that was sent to you and that you become very familiar with CAT and its functions. Many of your queries would have been answered if you had done this homework in detail. Ray Arvidson
  21. Yes, although the Viviano-Beck paper that we sent to you shows which bands to use for her indices. If you use your own indices and select accordingly. Ray Arvidson
  22. It should be a monochrome image with bright areas indicative of a high value for the spectral parameter used, yes. Ray Arvidson
  23. Result is one monochrome image. Do your band math in sensor space, use CAT to flatten the result, and then project. Results will have to be your task. I do not know where the pyroxene is located. Ray Arvidson
  24. Your band math seems to be missing parentheses at the appropriate places. Please read the band math documentation for how to represent algebraic expressions. Ray Arvidson
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