3d effect optical illusion

So I have bought an app called The Elements (the piggiest of them all at 1.4 gb) and it loaded full of animations of all kinds of stuff from the periodic table. Anyway, all animations have the ability to be viewed in 3d, provided that your optical muscles are powerful enough to cross your eyes such that the two separate images on the iPad screen (about 10 cm apart) become one. I just want to clarify that this 3d effect is the sort of… Um ghettoish type. It’s not the type relying on dual color filters or polarized spectacles or synchronized alternate eye polarized monocles or anything fancy shmancy of the sort. So, I assumed naturally that the effect is achieved by having a 3d camera, with dual lenses capture the video of whatever lump of clay they’re spinning round, right? Wait, maybe wrong, because since the vast majority of these animations are some object spinning turn-table style, all you need to achieve a 3d effect is a single lens camera and simply offset the left/right image by one frame (on average of 2-5 degrees angular separation based on the number of frames for a full rotation). But then, I came to this one piece of video that I could advance/rewind with my finger frame by frame, the object being shot was a stationary dish of liquid oxygen and an incense-like stick being stuck in it from the side. Nothing was spinning, but I noticed that the left/right frames were of set by one (speaking in time domain)yet the 3d effect was still being produced by the brain. How is this possible? Can you simply put a time phase shift between the left and right eye images and obtain a 3d effect without needing a lens location shift?

Only in the specific example that you’re listing of rotation around the vertical axis.

Maybe. It sounds as though it could be related to the Pulfrich Effect (the conventional way to deliver that is to put a filter over one eye, effecting the change in timing just by reducing the light into that eye, so it takes marginally longer to trigger a response).

What exactly is happening in the liquid oxygen video, motion-wise?

The dish is stationary but the lit incense stick slowly comes in from the side and causes a fairly nice flame

Hmm, that’s interesting. Any way to post a couple of screenshots? Or do they have a sample available that we could look at? (Is that the one published by the same people who helped Stephen Wolfram put A New Kind of Science on the iPad?)