Re: The problem with Pulfrich

[P3D John Bercovitz <bercov@xxxxxxxxxxx> To: photo-3d@xxxxxxxxxxxxxxx]

>Try watching TV with half a pair of sunglasses. You will occasionally be treated to startling 3D when the camera pans left or right while following an actor or with a title placed over a moving scene. 

Actually, as long as we're being precise about words, panning is when you rotate the camera about a vertical axis, preferably approximately through the lens. This won't give you the Pulfrich effect because you won't get a different perspectives. There is a word for what you're talking about, but I can't remember it. At any rate, the camera has to translate relative to the objects (or vice versa) to get the effect. 

>It does tend to have the "cardboard cutout" sensation because the whole of an object is usually moving at the same rate. 

I think the cardboard cutout effect you're seeing is probably due to the usual cause which is poor resolution. With very poor resolution, you can only see the grossest stereo disparities. A gross disparity would be between a nearby person and a distant background, not between the tip of a person's nose and his eyes if the person is standing at any distance, for instance. It's amazing how fine the resolution of the eyes is in stereo mode. TV sets have rather poor horizontal resolution. 

John B


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