Grab your 3-D glasses
For orbiting spacecraft a trick with spacecraft orientation can be used to get 3-D information on the terrain of a planetary body. If images of the same region are taken at different angles, these images (usually taken as two images called stereo pairs) can be combined to make stereo or 3-D images. This is the same technique our brain uses to generate depth perception. This is because our eyes are spaced apart, each eye has a slightly different view of the things in front of us. Our brains automatically combine the information from the two images to gauge the distances to and construct the sizes of objects in our vision.
The HiRISE team does this by commanding the Mars Reconnaissance Orbiter to point such that the HiRISE camera rolls either left or right of the ground track of the spacecraft as its above a target region. This technique has been used to created digital terrain and elevation models of the landing sites for the Mars rovers and other areas of interest on Mars. Anya from the Planet Four team is working on analyzing a stereo pair of the spiders as she mentioned in one of our previous live chats.
A popular way to view a stereo pair from orbiting spacecraft is in what is called a stereo anaglyph where the images are combined such that there is one image for the left eye and one image for the right eye. The left looking image is displayed in red and the right looking image is displayed in blue. If you have a pair of red-blue 3-D glasses, you should see the the above image in 3-D.
I happened to come across an analgyph (the image above) of the seasonal fans taken during the monitoring of the South Pole in Season 2, and I thought I’d share. The full resolution 3-D image can be downloaded from here , and you explore the full-res image with zooming and scrolling capability with the HiView tool. Grab your 3-D glasses and enjoy!