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.