Below is an example that shows pairs of perspectives in an animated presentation. The left basketball is setup to be viewed by your right eye and the right basketball should be viewed by your left eye. The two tiny gray squares at the very top are used to help you cross your eyes. What happens is as you cross your eyes the dots will move inward and when they are on top of each other your eyes will be crossed in a way that aligns the two different images to a point where you can fuse them into a single view with depth. It can be tricky to do and many people have a great deal of difficulty but I encourage you to give it a go. Of course, my autostereoscopic 3D photographs don’t require you to cross your eyes and you see the hoop stick out of the photograph in a natural way.