Stereoscopic rendering Questions

[ben_hamburg]

Hi,

so right now I´m working on my second stereoscopic project and it hasn´t been much of a hassle, but mostly because I didn´t play around too much with the settings, but only because it´s hard to find some in depth explanation of the settings, so here are a couple of questions:

1. How to the focus and the zero plane correlate? By zero plane I mean the stereoplane that connects with the real edges of the monitor, not sure about the terms.
As far as I understood, objects behind the focus point (be it from the automatic focus determined by the camera target, or set through "specifiy focus") should be further "inside" the screen, whilst objects in front of the focus pint should pop out of the screen, right?

2. Can you give me some examples of why to use which focus method?
So far I´ve only used "shear".

On a sidenote: I guess it´s a known Issue, but render elements don´t work with "adjust resolution", if you don´t use the vray frame buffer to save out your files. Would be nice to have a note for that in the help file, unless it´s already been fixed in Vray 3.0 (still on 2.4 atm)

[t1t4]

1 - Most of the time what you are referring to as the zero plane is called the screen plane. It sounds like you are mostly getting how to determine what is in front of and behind the screen plane. Maybe you already know this but you can separate the screen plane distance from the focus distance. At least using the vray stereo helper you can easily do this with the "specify focus" option. That only applies to the stereo focus (usually called screen plane) not your dof/camera focus. When the helper is selected it displays the screen plane as the end of the camera view cone making it easy to see what is in front and behind or even right on the screen plane.

One other thing to keep in mind is that you can always shift the screen plane in post by sliding the left and right images horizontally. For stereo rendering it's good practice to render with extra padding on the sides so that you can do post stereo shifts this way. Helps when trying to cut shots together by blending stereo focus from back to back shots where it is very different. Also to tweak what is in front or behind the screen plane a little. There are also fun things you can play with as well like the stereo window where you can make it look like the screen plane is closer than it really is by cropping the sides of the image. The stereo window can be used to make shots work a lot better than always having the image go to the edge of the screen. I could elaborate a bit more on this but I'm sure there is information on the web as well.

2 - I don't know when you would want anything other than shear. It tends to work best for most things. If you use rotation you will end up with a bit of perspective warping / mismatching between eyes which will cause the left and right sides of your images not to line up well. I'm sure there must be a time when rotation or parallel ("none" in the vray helper) would be better but I don't know what that would be. I think parallel is maybe a bit more useful than rotation. Not sure but maybe for HMDs it would work better but that will also depend on how you want things viewed.