The cameras on the back of the DS can be used to create visual effects in 3D.
"One of the best showcases for the technology was an ‘alternate reality’ game called Target Shooting. This game makes excellent use of the 3DS’s features in ways I haven’t seen before. Here’s how it works: you point the 3DS’s out-facing camera so that it can see a printed Question Mark block (from Mario) placed on a table in front of you (in the real world), which you can see on the Nintendo 3DS’s. After a quick calibration process, that question mark block vanishes from the screen completely and becomes a virtual canvas on which the game is played. Now keep in mind that this “canvas” resides within the “real world”--that is, you can still see your physcial room outside the boundary of the virtual landscape, blurring the lines of fantasy and actuality.
At first, a tree and three targets popped up. To aim, you physically move the 3DS around in actual space to position the targets in the center of the screen, as if they were actually there. You can move the 3DS closer or further and even side-to-side--basically anything you need to do in order to get the targets on-screen. After we destroyed those three, the virtual landscape magically transformed before our eyes, causing a deep recession to appear in the ground. The game then instructed us to “look” into the hole. I then actually stood up and moved my 3DS directly over the hole (or in real life, the Question Mark block on the table) and found my final target, which I was then able to blast. Let me be frank: this blew my mind. Actually moving the 3DS around as if it were a window into another world really does feel out-of-this-world.(Andre Segers/gamexplain.com)"
Links:
http://www.gamexplain.com/article-148-1276728398-e3-2010-target-shooting-nintendo-3ds.html
http://gonintendo.com/viewstory.php?id=127205
If Nintendo is successful at the moment, it’s because they are good, and I cannot blame them for that. What we should do is try to be just as good.----Laurent Benadiba
