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sftrabbit
Up and Coming
June 4, 2013

Why do Vireio Perception and VorpX have convergence?

I've been studying some of the maths behind VR and HMDs, and I'm confused about one thing in particular. Both the Vireio Perception and VorpX drivers provide convergence settings. In fact, VorpX automatically converges the virtual cameras on whatever object is in the centre of the screen, according to a blog post.

What's going on here? I was almost certain that, since the player's eyes are directly axis-aligned with the two halves of the screen in the Rift, the virtual camera projections should also be axis aligned. The player's eyes will do the converging within the Rift, not the cameras within the virtual world. It seems to me that applying a convergence to the cameras would cause a strange distortion.

Can anybody help me understand this? Thanks.

    3 replies

    cybereality
    Inspiring
    June 6, 2013
    At least with Vireio, the "convergence" really just adjusts the overlap of the images. It's sort of like taking two photographs on a table and moving them closer or further from each other. It doesn't actually effect the rotation of the camera, that is always facing directly forward (parallel to each other).
    AMD Ryzen 7 1800X | MSI X370 Titanium | G.Skill 16GB DDR4 3200 | EVGA SuperNOVA 1000 | Corsair Hydro H110i Gigabyte RX Vega 64 x2 | Samsung 960 Evo M.2 500GB | Seagate FireCuda SSHD 2TB | Phanteks ENTHOO EVOLV
    Wileythecoyote
    Up and Coming
    June 26, 2013
    "What I’d like to talk about today is how 3D (optionally!) is done in vorpX."
    There's nothing wrong with offering options to play around with :)
    ralfal
    Up and Coming
    June 27, 2013
    It's simliar in vorpX, even more so with Z-buffer 3D. The illustration in the blog post that was mentioned by the original poster is a little bit misleading, it's just there to give a general idea about how things work.

    The zero parallax plane, which is essentially the thing defined by convergence, has a predefined z-value that fits an HMD in vorpX and it's not changable unless you explicetely tick a checkbox that allows you to tinker with settings that shouldn't be tinkered with by normal users.

    The optional! adaptive algorithm does change 'convergence' in a way (automatically), and that might indeed sound counterintuitive, but it works surprisingly well. To quote someone slightly more intelligent than I am: “In theory, theory and practice are the same. In practice, they are not.” ― Albert Einstein
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