3D

[Bassman]

Ok, this part of the forum is for anything of interest not just FSX? On that assumption I would like someone to explain Avatar's system of 3D.

My specific query relates to the screens used.  At the theatre, Avatar is shown in 3D without any modification to the screen; so the effect must be in the projection onto the flat screen which is why we still need 3D glasses. As the 3D effect is in the picture and does not rely upon a special screen, why do we need special 3D monitors or the new range of 3D televisions?

Cheers  Dan

[Ken Hall]

something to do with refresh rates, 60 hz won't cut it as were looking at 2 separate images one left eye one right eye, we need 60hz per eye minimum, so 2x60 =120hz. The glasses merely separate the images, with the nvidia setup they use similar technology to automatic welding goggles, where the goggles shut out the light when you start to weld, a sensor detects the bightness level and the lens darkens. with the 3 D what happens is they shut the right lens of the goggles covering obviously the right eye, at the same time the left eye is left to see the image. then they reverse the process for the other eye. so each eye gets a different view, and we interprate that as 3D. clear as mud eh, but essentially we need more frames per second because we are displaying twice the no of frames per second. Not sure how the Cinemas do it, perhaps the goggles there may be polarised each so each lens is polarised to suit the image each  eye is meant to see. It would be interesting to swap left and right lenses and see the effect, Warning "Don't try this at home kids"

[Bassman]

Thanks Kman. Begs the question why a normal home television cant be used with suitable polarised goggles like a cinema.

I think from seeing adds for actual 3D tv's, one still has to use goggles.

Anyway, thanks again for the reply.

Dan

[maxter]

My understanding is that there are 2 types of 3D TV's, active and passive.  Not sure which way it goes, but I think that the active version needs the goggles and the passive version just uses the glasses.  I did try out one with just the glasses and the 3D effect was pretty amazing.

Cheers,

[Derek McAllan]

3d in the cinema, the modern version of it anyway, is based on polarised light.  You've got 2 projectors projecting the left and right images through a pair of polarising filters at right angles to one and other, and the glasses have their left and right lenses polarised to match.  If you take the glasses off the image still looks relatively normal because your eyes aren't differentiating the separate polarised signals.

3d TV's on the other hand are more or less as kman said, and the reason that the old TV's don't cut it for 3d is indeed the refresh rate.  You can't (easily) do the polarised light method with a tv as it is working with a single light source and a single filter, ie- the lcd panel itself.  Of course, if you're cashed up enough, you could do it properly with a pair of projectors in your home theatre 

[mjrhealth]

3d tv uses mpeg 4 technology, and requires the glasses be synced to the tv vis Infrared, just like the remote. Glasses use batteries, apparently some can be recharged, The cinema uses polarizing lenses, had a look at the 3d tv the other day, quiet impressive. Of course tvs that dont have the correct 3d hardaware simply display the 2 pictures side by side, whereas the 3d tv, stretches both pictures to screen size, and without the glasses look not much different to the cinema one.