I see that the USGS now has some very high resolution elevation maps for some parts of Mars:
The good news:
It really is very fine resolution, good enough for ripples on the dunes from what I can see.
The bad news:
Downloads are HUGE, (over 1 Gb!)
I'm really struggling to find something that can make sense of the data, even the image maps, (which I would have expected to be straightforward).
Has anyone else managed to get at the data in a usable form, e.g more widely supported image format, DEM, terragen, vue etc?