A little late to the party, but just wanted to add my 2 cents in case it helps someone make a full dollar :)
@Thomas: the process Michael described above is exactly what you need if your starting point is already a world position pass. You should only need the pass rendered for one eye and the opposite camera to get disparity data. Unfortunately, this is a lot more tedious to do with standard nodes than it would be by writing a dedicated plugin, specially if you want to account for any possible variation with the Cameras. For example, you can get the transformation matrix of your cameras from their world_matrix knob, but you can't get the projection matrix (unless you're writing a plugin, that is). So, you need to manually figure out the camera-to-screen transformation using the knobs from the camera's projection tab. For simple cases, you can use just the focal and horizontal aperture values, but if you need to account for window_translate, window_scale and roll changes, then it gets messy very easily. That said, I've put together a little Nuke script (attached) to go from world position to disparity. It could be more compact, but it's split out to show the different transforms and conversions between coordinate systems one by one, so hopefully it'll be easier to understand. Keep in mind that, as stated previously, this one doesn't account for changes to the win_translate or win_scale knobs, though. Hope that helps. Cheers, Ivan On Sun, Apr 1, 2012 at 12:52 PM, Michael Habenicht <m...@tinitron.de> wrote: > Hi Thomas, > > you are right the pworld pass is already the first part. We have the screen > space and the coresponding world position. But to be able to calculate the > disparity you need the screen space position for this particular point > viewed through the second camera. It is possible to calculate this based on > the camera for sure as this is what the scanline render node and reconcile3d > node do. But don't ask me about the math. > > Best regards, > Michael > > Am 01.04.2012 18:08, schrieb thoma: >> >> Hi Michael, >> >> We're using Arnold. If i have my stereo Pworld passes and stereo cameras >> in nuke couldn't i make this work? When you say world position projected >> to screen space isn't that essentially what a Ppass is or are you >> talking about something more? I tried doing some logic operations on the >> left and right eyes of the Ppass to see if it would yield anything >> meaningful but no luck.... >> >> Thanks >> Thomas >> >> >> _______________________________________________ >> Nuke-users mailing list >> Nuke-users@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/ >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users > > _______________________________________________ > Nuke-users mailing list > Nuke-users@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
world_to_disparity.nk
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