[Bf-cycles] Mirror ball crop
vitos1g at gmail.com
Fri Jun 22 13:35:07 CEST 2012
i think the main problem/issue is image sequence support for material
nodes(for world material)
Date: Thu, 21 Jun 2012 15:11:46 +0200
> From: Brecht Van Lommel <brechtvanlommel at pandora.be>
> Subject: Re: [Bf-cycles] Mirror ball crop
> To: bf-cycles at blender.org
> <CAKFUgC1uCHPsOfB6R3o+UHHw+iZifGhkk2_Ydf-KDmGuZMVk+g at mail.gmail.com
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> In principle it's of course possible to do this. There exist circle
> detection algorithms if this needs to be automatic, but that needs
> quite a bit of coding time. Or it could perhaps be done more manually
> by keyframing a mask in the tracker, but then I guess still missing is
> some automatic way to crop the image to the bounds of the mask, which
> is not particularly hard to implement.
> On Thu, Jun 21, 2012 at 12:45 PM, Tony Mullen <tony.mullen at gmail.com>
> > Hi Dalai,
> > Thanks for the feedback.
> >> Have you considered capturing it with a fisheye instead or a mirrorball?
> > Well, the first bottleneck is budget. I have a DP with a Red Epic, but
> > he doesn't have a fisheye lens for it. I can look into buying him one,
> > but it might be a bit costly for me.
> > The second thing is that what I had in mind was to shoot ordinary,
> > undistorted movie footage using the mirror ball to stand in for the CG
> > object, and then crop that mirror ball out and use it as a
> > light/reflection source, then composite the CG object back into the
> > original movie footage. This way, all the live action stuff would be
> > shot once, and the reflections would be automatically captured on the
> > surface of the mirror ball.
> > Basically something along the lines of this:
> > http://www.hdrv.org/IBL.php
> >> Either way I think you will have a better luck by pre-processing the
> >> into any of the standard inputs that blender can take. Or the processing
> >> time is your bottleneck?
> > I imagine it shouldn't be hard to export the HDR video to a sequence
> > of .hdr still images (I'm not 100 percent how to do this in Redcine,
> > but I guess it can be done). The tricky part is cropping it to fit the
> > Cycles mirror-ball mapping requirements. I guess there are probably
> > tools somewhere that can be used for batch cropping HDR video frames,
> > but I'm not sure how to do that. If it could be done in Blender it
> > would be pretty handy, I think.
> > Keyframing the crop was just an idea I had to make the setup more
> > flexible. I think it could be pretty powerful. Basically a silver ball
> > anywhere in a live action scene could be cropped out and used as an
> > accurate light source, even if it moved around within the shot.
> > T
> >>> Hi all,
> >>> I'd love to use HDR video from a Red Epic as a light/reflection
> >>> source. It seems like the best way to do this would be to use an HDR
> >>> video of a mirror ball, and use the mirror ball mapping. It seems like
> >>> it would be quite helpful to be able to crop the image from within
> >>> Blender. For example, to place and scale a circle in the UV Image
> >>> editor to tell Cycles what part of the video frame to use as the
> >>> mirror ball.
> >>> Even cooler would be to be able to keyframe the size and placement of
> >>> the cropping circle, so that you could "rotoscope" the position of the
> >>> mirror ball within the frame, enabling the camera to move more more
> >>> freely (the light source would then be mapped to follow the camera's
> >>> movement within the 3D space).
> >>> Does this sound like something that can be done, or is anybody
> >>> planning to implement something similar?
> >>> Regards,
> >>> Tony
> >>> _______________________________________________
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> >>> Bf-cycles at blender.org
> >>> http://lists.blender.org/mailman/listinfo/bf-cycles
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