Re: tilted horizon and other forbidden practices... Message-ID: <199605240259.CAA25707@xxxxxxxxxxxxxxxxxxxxxxxxx>

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxx> To: photo-3d@xxxxxxxxxxxxxxx]

Tilt is one of those things that you might not notice at first, but once you become aware of it, it bugs you to no end! Sometime ago I told the story about coming back from my vaction to Greece. I had a dozen or so pictures taken with a tripod, that included sea level. The camera was tilted! It drove me crazy! I threw all of them away except for one or two which I tried to save by rotating the two chips (now this introduces real misalignments, but they can be less annoying than the tilted horizon!)

In real life, when I tilt my head, somehow my brain compensates and I still DO NOT SEE a tilted horizon. But in a viewer the tilted horizon in there and it is very annoying. Again, you might not notice it at first, but if someone points to it, it becomes really annoying.

But, without a clear indication, like the sea level, it is usually difficult to notice a slight tilt. Joel Alpers (I think) mentioned that he started noticing tilt and tilted horizons in 2-d pictures which also became distracting.

Greg wrote:

> I'm sure I've read somewhere, stated as >gospel truth, that such rotation is absolutely forbidden. 

There are a few things in 3-d that are absolutely forbidden and tilt is not one of them! A little bit of tilt with a clear sea level or horizon in the picture can be a problem, but some people have used considerable tilt (90 deg.) for special effects. 

Tilt is anoying but it is harmless compared to other mistakes that cause eyestrain (tilting the camera does not cause eyestrain) like using SLR cameras fitted with different lenses (I have done it!) Bad mounting should be forbidden and punished too! ;) Same for subjecting an audience to boring slide shows... 

George Themelis


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