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thinkinmonkey

Stereoscopic cameras from scratch

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Hello everybody,
I need to render a stereoscopic 360 animation with C4D/Octane.
Now, to make the story short, we have already rendered the monoscopic/normal sequence and we are gonna to render the stereo one, but I was wondering if it was possible to use the already rendered sequence as left eye and rendering a new sequence for right eye just shifting the camera.
I know it's not the same especially for subjects close to the camera, but actually we can live with that as we have very few scenes that could need a proper stereo render.
Houdini gives a value of 0.075 as interaxial distance, so I'm using that for the moment with a camera parallel to the previous one.
Do you think it's enough to shift the camera or I should take in consideration also other parameters?
Thank you a lot in advance.

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Our stereo panos tend to be that; keep one eye as-is, shift the other. Apart from the usual reducing stereo towards the top and bottom of the pano, we didn't do any other tricks. 

 

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Hi Matt,

thank you very much for your answer, so no I can be more sure about my result.

Only one question, if I can: what do you mean with "apart from the usual reducing stereo towards the top and bottom"? Do you do something about top and bottom part of the image? Thank you.

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Stereo panos only really work if you look flat at the horizon. As you look straight down or straight up the left/right separation is broken, because the stereo shift you apply at the horizon can be seen at the poles as a 'twist'. 

Most stereo pano cameras allow you to fade out this twist at the poles, so essentially looking straight up and straight down the pano is mono. 

More info here, scroll down to 'pole merging':

http://pedrofe.com/oculus-camera/

 

 

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On 11/17/2017 at 12:20 PM, mestela said:

Stereo panos only really work if you look flat at the horizon. As you look straight down or straight up the left/right separation is broken, because the stereo shift you apply at the horizon can be seen at the poles as a 'twist'. 

Most stereo pano cameras allow you to fade out this twist at the poles, so essentially looking straight up and straight down the pano is mono. 

More info here, scroll down to 'pole merging':

http://pedrofe.com/oculus-camera/

 

 


You can also build L/R functionality into a houdini/mantra or Arnold lens shader. I've done this for both pano (equirectangular) and equidistant immersive lens shaders.
Basically, each pixel (or sample, for that matter) is rendered as viewed from a different point in space, calculated by your shader. In the case of the equidistant lens shader, I got around the issue of twisting divergence vectors around the poles by offsetting my ray origin by a fraction of the derivative of my projection ray with respect to image plane x. (This is for a forward facing 180 degree "fisheye" stereo view). It works nicely and while there is some angle/shape to the divergence vector field, it's pretty natural and conforms nicely to the way you would naturally look around within the projection environment...

Can't speak to other renderers/cameras... Also thanks to SideFX for granting my feature request a few years ago to make this possible with path tracing!

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@mestela, thank you for the link, I'll have a look before rendering.

@henderthing, thank you for your sharing, but a) I'm not that good :) and B) I'm using Cinema 4D and Octane, I'm not sure if they have all that control you have with Houdini (of course you have more control inside Houdini, that's one of many reasons we chose it!  ;) ), but I think that rendering another sequence for the other eye and fading the two sequences in post with some blurred mask will work. I hope.

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