[X] My Assistant

[Guest_AlexBlackwell_*]

August 29, 2007, HiRISE release

Interesting new image of the Arsia Mons pit.

The polar pit gullies image is pretty good, too.

[dvandorn]

You obviously observe vertical and near-vertical surfaces from a slant angle. Now, as good planetary imaging afficienados, we tend to think of getting the greatest resolution, and the greatest resolution (and most useful angle for projecting our images onto DEMs or using them for mapping) is from directly above.

But especially in the game of reconaissance spacecraft, what you want to look at might not pass directly underneath the resource(s) you have in place. So, you end up working a series of compromises; do you want 15-cm resolution of the ground 112 miles away from what you really need to look at, or do you want 23-cm resolution of what you need to see, at a slant angle of, say, 17 degrees?

And, of course, there are times in the recon biz when you *want* to see things from a slant angle, when you need to analyze an object or a construct in three dimensions. There is only so much you can do to reconstruct something's shape from a direct overhead shot and a short shadow...

-the other Doug