Stereo Pics. Theories of 3D (Part 2)
Still fumbling my way towards a new idea about how we see in 3D, or more specifically how we see stereo pictures as 3D.
Brian May has some beautiful examples on his site at the moment, of crocus flowers. I've reproduced them below, having now acknowledged the source! The first is for 'free viewing', which means you have to look at the two images but be actually looking to infinity beyond the screen i.e. you have to 'look' at the pictures but actually be looking as if you were watching something miles away in the distance. This seems impossible at first, because you'll tend to want to focus on the screen itself, and you might also think "how can I look at two things at once?". But it's a sort of peripheral awareness of the flowers, while looking with your eyes aimed to infinity, just as you can be aware of both the road in front of you (to infinity) when driving and what's going on in the car (peripherally, like the flowers in this case).
[I suspect it's peripheral awareness that's the pathway to a proper understanding of how stereo photos work, but it's still a bit half-baked in my mind. But it doesn't necessarily explain why some colours on computer screens jump out at you in 3D, as I wrote about back here.]
As you get good at this you'll notice that the two images turn into three, and then keeping your eyes diverged as if they were looking into the distance, you focus on the middle of the 3 images. Again at first it seems impossible to be focusing on the close thing while 'looking' far away. But using the car example again, you can be both watching the road ahead and peripherally focus on the radio knobs, at the same time. As you focus on that middle image, and it can take a few seconds for the focus to sharpen (and it will - give it time), it will jump out at you in glorious 3D. Anyway, the 'free-view' version is below, to try using what I've just described.
Now here's the 'cross-eyed' version. To view that you just cross your eyes i.e. go cross-eyed, until you get 3 images. Then you focus on the middle of the 3. Many people find this easier, as did I at first, although after a while you get fed up with being cross-eyed.