Hi!

Yes, tried that and it kind of works. I used a checkerboard, let Photoscan 
apply the same distortion than on the real frame, and used that in Nuke with 
the grid analyze mode of the lensdistortion node. Problem is: the algorithms 
are different, so both results don't match exactly. Would be better than 
applying no distortion, but using a node with identical algorithms should give 
more precise results.

Abraham


Am 13.05.2014 um 14:05 schrieb Elias Ericsson Rydberg:

> You could export your undistorted plate from Photoscan, match that distortion 
> in nuke with the LensDistortion node. Then change the input on the node to 
> use your CG and have it distorted.
> 
> If you could use any distortion values from Photoscan that would be nicer, 
> but this could also work?
> 
> Cheers,
> Elias Ericsson Rydberg
> 
> 
> 2014-05-13 12:02 GMT+02:00 Schneider, Abraham <[email protected]>:
> Yes, I know about that. But I don't want to undistort my plates. I'd like to 
> distort the CG renderings and merge them with my original plates. So I have 
> to 'invert' the undistortion that Photoscan does and apply this to CG 
> renderings. I'll get the parameters of the undistortion inside of Photoscan, 
> but would need a node in Nuke where I can use these values.
> 
> Abraham
> 
> 
> Am 13.05.2014 um 11:30 schrieb Misho Ristov:
> 
> > You can export undistorted photos from photoscan and use that directly in 
> > Nuke
> >
> >
> > from memory:
> >
> > tools->undistort photos
> >
> >
> > Misho
> >
> >
> > On 12.05.2014 23:07, Nathan Rusch wrote:
> >> I think one of the 3DEqualizer distortion models is based on the Brown 
> >> model. If that's the case, there's a good chance you can use their 
> >> distortion plugin to get the same result.
> >>
> >> Details here:
> >>
> >>
> >> http://www.3dequalizer.com/index.php#?site=tech_docs&id=110216_01
> >>
> >>
> >>
> >> -Nathan
> >>
> >> -----Original Message----- From: Schneider, Abraham
> >> Sent: Monday, May 12, 2014 5:25 AM
> >> To: Nuke user discussion
> >> Subject: [Nuke-users] Photoscan lens distortion in Nuke?
> >>
> >> Hi there!
> >>
> >> I'm just playing around with Agisoft Photoscan (
> >> http://www.agisoft.ru/products/photoscan/standard/
> >> ) to deal with a large set where I have to do some CG additions in several 
> >> shots. Most of the shots are with locked camera. So having a rough temp 
> >> model of this outdoor set (big square with some buildings surrounding it) 
> >> would be really helpful to correctly position the CG buildings.
> >>
> >> Reconstructing the set with Photoscan from my DSLR images worked quite 
> >> nice. The resulting model should be more than enough to help creating 
> >> these shots. My idea now was to add single frames from each of my locked 
> >> camera shots (ARRI Alexa) into Photoscan, align these images as well and 
> >> export the found camera positions with the model and use these virtual 
> >> cameras for my renderings.
> >>
> >> Problem now is: to align all the images, Photoscan uses an complex (?) 
> >> lens distortion algorithm and undistorts all images before doing there 
> >> alignment. So the undistorted images match fine to the model from 
> >> Photoscan. But to do my comps, I'd have to it the other way around: 
> >> distort the CG renderings and merge them with my original Alexa footage. 
> >> So I'd need a node in Nuke to apply the same lens distortion as Photoscan 
> >> does. I get the values from Photoscan, but which node can I use to do the 
> >> distortion?
> >>
> >> I think, Photoscan uses the same model as they use in their free lens 
> >> distortion software:
> >> http://www.agisoft.ru/products/lens/
> >> , which mentions a 'Brown's distortion model'. Anyone of you knows if 
> >> there is a node in Nuke (or Nukepedia or so) which uses the same 
> >> algorithms? Or any other idea?
> >>
> >> Thanks, Abraham
> >>
> >>
> >> Abraham Schneider
> >> Head of VFX pipeline / VFX Supervisor
> >>
> >>
> >> Türkenstr. 89, 80799 München /
> >> Phone +49 89 3809-1096
> >>
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> >> [email protected]
> >>
> >>
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> >>
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> >>
> >>
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