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I am currently working on a school project and am trying to download topographical images of Mars at high resolution. I am still trying to figure everything out on the sites and learn how to use the Mars Orbital Data Explorer. However, I am running into the issues of my downloaded files being corrupt for some reason. I am following the instructions from the User Manual the best I can, but it does not seem to be working. I add the items I want to my cart, and when I receive the email confirmation, I download them using FileZilla. When I try to open the .img files though, I get an error message saying the disc image is corrupt. I have also attempted to convert those files into PNGs using the IMG2PNG tool that was recommended on this page http://www.planetary.org/explore/space-topics/space-imaging/data.html?referrer=https://www.google.com/?referrer=http://www.planetary.org/explore/space-topics/space-imaging/data.html. However, when I do the conversion, I just get a black image (presumably because the file is corrupt).


Basically what I want to do is to create heightmaps (bitmaps) of Mars based on the data collected by NASA on various missions. I cannot seem to figure this out though. I plan to use the generated heightmaps to create partial landscapes in Unreal Engine, which happens to want them in PNG format, so I thought this would be perfect. The issue is the downloads don't seem to work, and I would eventually need grayscale images anyhow (which I also can't seem to find on the site, though I am unsure how to specifically do that).


Hopefully I have provided enough information here. If anyone has any suggestions or needs more information, please ask.


Thank you.

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Hi Jgeer,


Would you please let me know which *.img data you downloaded yesterday? There were a few downloads yesterday in our cart system. I am not sure if the below 4 data in two separate downloads were yours.






If yes, I used the IMG2PNG tool to convert those img to png succssfully.  megr44n090hb.img is a shape map of Mars. megt44n090hb.img is a topographic map of Mars. You may see something like below Fig. 1 using ArcGIS tools or open the png with Windows Photo Viewer. megc*.img contains the number of observations per pixel used to produce the data products. You will see a png with lots of white spots in a black background as Fig. 2. The megc*.png was shown in all black in Windows Photo Viewer for me. You may use another visualization tool for those pngs. The black is probably the gray values were not stretched when they presented them. 


As for the corrupt message, I am not sure which software you used to open the data. It might be the software you picked may not be the right tool to open them, or the data you downloaded were corrupt during the downloading. Would you please give me some more details so I may have some hint, or please try to download one more time to see if there is any difference in your transaction?  Feel free to let me know what you get and I am happy to help you with the data.





Fig. 1




Fig. 2,

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Thank you for your response. You were correct in assuming those four downloads were mine. And also right in that it was like the software used in my attempts to view them. I am not sure what ArcGIS is but may look into that. After a bit of work I managed to get the PNG file conversions as you have said.


I think my main issue was with the file megr44n090hb.img I tried to use, as it was not a topographic map as I had anticipated and so it did not turn out how I thought it would. The others now seem to work great, though. And it loaded into my Unreal project perfectly. I am still working to find downloads of smaller regions of Mars, but I think I can figure that out from here. Again, thank you for your response. You definitely helped shed light on some issues that I had.

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Hi Jacob,


Glad to know you made progress on this. PDS has lots of different products. If you are not sure about certain data, always refer to the attached or detached labels (e.g., *.lbl), which will includes the description of the data product. And the product SIS file is also a good resource for the users. Feel free to let us know if you need further help. Thanks,



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  • 5 months later...

Hello, I am currently running into a similar issue as it seems people have before. I am writing an importer for Blender3D to use altimeter data from Mercury and Venus orbiters to create 3D height maps(spheres) of the two planets. The importer is done aside from reading in the data in the correct order. Sadly, I have no way of knowing how the information is ordered in the various .IMG files. When I try to mount them I am confronted with an error that states "The chosen file is corrupted". Any ideas or hints are appreciated. The file I have been using most recently is "MSGR_DEM_ASU_EQ_CATLS01_CF_85_I_V01.IMG". Again thank you for your time and any advice you can give. 

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This is a DEM product generated by Arizona State University using MDIS-NAC images in Equirectangular projection. From the label file "˜MSGR_DEM_ASU_EQ_CATLS01_CF_85_I_V01.LBL', you will find this is a 1-band data with below information.

    LINES                              = 404
    LINE_SAMPLES               = 392
    SAMPLE_BITS                 = 8
    SAMPLE_BIT_MASK        = 2#11111111#
    BANDS                             = 1

ENVI can read this PDS IMG data. Gdal would also read this IMG data and transform it to another format such as Geotif with gdal_translate command. Gdalinfo command helps to give you a summary of the product details. Please let me know if this helps or if you need more information. Thanks!


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