3D Mars Scenes Recreated From Photos

Hoon Mihn Fao links to this BBC article about Microsoft Research scientists generating 3D models based on pictures beamed back from the Mars rovers. It begins "Using techniques originally applied to paintings, the researchers have written software that works out what flat images would look like from different viewpoints. The result is a navigable 3D model created from one or more pictures snapped by the Mars buggies."

Comments

Mars in Stereo

[stereo_Barryo]

To repeat myself, my friend Robert Clemenzi has put up a page on Mars in stereo and has written a program, that can be downloaded, that allows you to study the pictures from the rovers in either cross-eyed stereo or over-under. http://www.cpcug.org/user/clemenzi/science/MarsIma ges_3D.html

Where's the video?

[Gyler St. James]

Wow. They said something to the effect of being able to see other objects that was not completely visible in the image. "We work out what's behind an object and how we can automatically fill in what's not seen by cameras or painted." I wonder if this would allow you to rotate around objects that are halfway hidden, but what about asymmetrical objects? How can they extrapolate what's not known? Interesting none the less, but where's the video they talked about?

Re:Where's the video?

[Tablizer]

How can they extrapolate what's not known?

I don't think they do. You can calculate the position of most objects actually imaged in images taken from multiple viewpoints of the same scene using a modern version of old-fashioned triangulation like surveyers use, but you still have no idea what is behind a rock, for example. At best one can guess what the back looks like based on the front (if back not imaged).

But I notice in some of the 3D models used by the Mars teams that "unknown" areas are filled in with gray. For example, a rock may have a gray "tail" for the areas that were not imaged. It is kind of a "viewpoint shadow". It might be safer scientifically to just have a gray tail instead of guess. Otherwise you may accidently plan rover journeys to places not actually imaged.

I notice I tend to do the same thing in my brain. I build a 3D model of the scene, and mentally fill in the hidden parts with kind of a grey or nebulous fuzz. If safety is not an issue, then I might extrapolate based on what is visable, but if safety is an issue (such as driving), then I tend to color the unseen area with a vivid color (like orange) that means "be careful, unknown territory".