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Susie Slavney

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Posts posted by Susie Slavney

  1. I believe the Matlab function "fread" would be the correct way to read a binary file, although I have no experience with Matlab. You will need to know the size and data type of the .img file, which are given in the corresponding label file (.lbl). In the label, look for the keywords LINES, LINE_SAMPLES, SAMPLE_BITS, and SAMPLE_TYPE. 

    For example, for the product at your link above, the label shows
     LINES = 52224
     LINE_SAMPLES = 5064
     SAMPLE_BITS = 16
     SAMPLE_TYPE = LSB_INTEGER (this means least significant byte first, or little-endian)
    The label also tells you that the file has 104449 records, each one 5064 bytes long, and the image data start at the second record. So you'll have to skip the first record.
     RECORD_BYTES = 5064
     FILE_RECORDS = 104449
     ^IMAGE = 2
    I am guessing that the Matlab commands would be something like this:

    fid = fopen('m1185002263rc.img', 'r');     % Open the file to read
    status = fseek(fid, 5064, 'bof');          % Skip 5064 bytes from the beginning of the file
    a = fread(fid, [5064,52224], 'int16' 'ieee-le');   % Read in a 5064x52224 array of little-endian signed 16-bit integers

    Again, I am only guessing about the Matlab commands based on information I found online here.

    The image pixels are stored in the file in order from left to right, top to bottom. I understand the fread statement fills the array in column order. So you might have to transpose the array to get it to display correctly. 

  2. Dear Shyam,
    To answer your questions:

    1. The '.tif' files are reduced-resolution, compressed versions of the '.img' files. They are browse images; that is, they are intended to be used for a quick look at the data to help choose products of interest. They are not suitable for science analysis because the data have been compressed. The actual LROC image products are in the '.img' files, and yes, they can be very large. Each '.img' file has an embedded text header at the beginning of the file that has the metadata for the product, including the size, byte order, and bytes per pixel. You could use this information in Matlab to read in the image. 

    2. I think there should be a .tif file for every .img file. The one for M1185002263RC is online here:

    For more information about the image products, look here:

    - Lunar Orbital Data Explorer's User Manual page about LROC

    - LROC EDR/CDR Software Interface Specification

    You might want to use the Lunaserv Global Explorer and the Quickmap 3D tools on the LROC web site, http://lroc.sese.asu.edu/archive

    If you need more help, I will put you in contact with someone at the LROC Data Node.


  3. Dear Shyam,

    I have forwarded your question to the PDS Cartography and Imaging Node, where the LROC data are archived, and to someone on the LROC team. I reminded them yesterday that we are still waiting for an answer. 

    I'm sorry for the delay.

    Susan Slavney

  4. Mars Odyssey Release 64 includes new raw data (EDR) , Derived Neutron Data (DND) and Derived HEND Data (DHD) products covering the period October 1 through December 31, 2017. Averaged Neutron Data (AND) and Averaged HEND Data (AHD) products cover the period October 17 to January 26, Ls 75 to Ls 120 in year 09. This release also includes revised EDR  and DND data from July 1 to September 30, 2017. The data are online at the PDS Geosciences Node at http://pds-geoscienc...dyssey/grs.html.

  5. Hi. I suggest you use the Orbital Data Explorer for Mars, http://ode.rsl.wustl.edu/mars/.  Choose the Data Product Search tab, and open the Step One options. Select the desired GRS data sets under the ODY (Odyssey) heading. Then narrow down your search by product ID, location, or other criteria in Step 2. You can preview your search results in Step 3, and finally submit your query in Step 4. You can select the products you wish to download from the search results list. 

    If you already know the ID or file name of the products you want, you can download them directly from the archive by following the links at http://pds-geosciences.wustl.edu/missions/odyssey/grs.html. Don't forget to download the PDS label that accompanies each product (*.LBL). It contains useful metadata about the product.


  6. SHARAD EDR data from the ASI team members have been posted, covering previous MRO release 43 and current release 44. With this release, the team has recovered data from deliveries that were missed due to a hiatus in ground operations. The EDR data set is now up to date. See ERRATA.TXT for details. The data are available on the PDS Geosciences Node's SHARAD page.

  7. Dear Sourabh,

    Only the CRISM TER and MTRDR derived products have been corrected for spectral smile. See these data product descriptions:


    The CRISM Analysis Tool (CAT) does not have code to do this correction. When we analyze CRISM data using CAT, other than for the two products quoted above, we pay attention to the shift in wavelengths as a function of column number. Note that in CAT, the center wavelengths used in spectral plots are those for the middle column only.

    CAT can be found at the bottom of this page: http://pds-geosciences.wustl.edu/missions/mro/crism.htm

    The center wavelength and bandpass file information can be found in: http://pds-geosciences.wustl.edu/mro/mro-m-crism-2-edr-v1/mrocr_0001/document/crism_dpsis.pdf. 


  8. Mars Odyssey Release 62 includes new raw data (EDR) , Derived Neutron Data (DND) and Derived HEND Data (DHD) products covering the period April1 through June 30, 2017. Averaged Neutron Data (AND) and Averaged HEND Data (AHD) products cover the period March 10, 2017 to July 8, 2017, Ls 330 in year 08 to Ls 15 in year 09. The data are online at the PDS Geosciences Node at http://pds-geoscienc...dyssey/grs.html.

  9. Alvaro,

    I took your question to Frank Lemoine on the MRO gravity team. His reply is below.

    Susie Slavney

    From Frank:

    "The uncertainties that are provided with a gravity model are derived from the diagonal of the covariance matrix of the spherical harmonic solution. They are representation of the coefficient error, but do not account for the correlations between the coefficients in the least squares solution.

    In order to obtain another realization of the gravity field solution that is perturbed according to the error information in the covariance, it is necessary to create clones, as discussed in this document (developed as part of the work on the GRAIL mission).


    For Mars, the GSFC team has created clones of the GMM-3 gravity model which might be suitable for the user. This model is described in the paper by Antonio Genova et al. (Icarus, 2016).

    The clones of GMM-3 are available at the following URL. http://pds-geosciences.wustl.edu/mro/mro-m-rss-5-sdp-v1/mrors_1xxx/extras/clones/

    The GMM-3 model is available at the following URL. http://pds-geosciences.wustl.edu/mro/mro-m-rss-5-sdp-v1/mrors_1xxx/data/shadr/gmm3_120_sha.tab

    The descriptive Label for the model is available at this URL. http://pds-geosciences.wustl.edu/mro/mro-m-rss-5-sdp-v1/mrors_1xxx/data/shadr/gmm3_120_sha.lbl

    If the user wishes to create clones for the JPL gravity model, they can either ask Alex Konopliv at JPL, or download the error covariance (the SHBDR file),  and follow the procedure in the above pdf document to manufacture their own gravity field clones.

    Frank Lemoine
    NASA Goddard Space Flight Center

  10. I asked the ODE developer if she could suggest a way to do this. Here's her answer. She reads this forum too.

    Hi Susie,

    Below link shows an example on how to read those MEGDR products  with Matlab. The user could modify the code a little bit to output a table with lat, lon, and height.


    Another way is to convert the PDS IMG to ERDAS IMG in ArcGIS. Then use ERDAS to convert the ERDAS IMG to an ASCII table with lat, lon, and height.

    Both Matlab and ERDAS are commercial software. Otherwise, the user needs to write his own program to read the PDS IMG data. The label includes everything that the user needs to know to read the data file.

    Please let me know if the user needs further help. Thanks,


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