By pixel perfect I meant compared to a rendered Z. I'm having really high values in my P pass (>100000), so it might be rounding off errors. I've tried with both 16 and 32bit renders though.
*I've found the easiest way is to do a coordinate system transform from world space to camera space then just take the Z channel. Note that, depending on the shutter angle of the render vs the imported camera keyframes that you may get a minor offset compared to rendering "in camera". * * * Interesting. Do you have an example setup to share? Cheers! 2013/5/13 Michael Garrett <[email protected]> > Yes, it's worth taking note of that and it's caught me out in the past. If > you take the vector from the camera position to any position coordinate in > the scene you're getting the true distance, whereas a Zdepth image is just > the z component of that distance. > > I've found the easiest way is to do a coordinate system transform from > world space to camera space then just take the Z channel. Note that, > depending on the shutter angle of the render vs the imported camera > keyframes that you may get a minor offset compared to rendering "in camera". > > Michael > > > On 13 May 2013 09:41, Eetu Martola <[email protected]> wrote: > >> Most renderers write Z as orthogonal distance to the (extended) >> cameraplane, instead of the actual distance between the pixel position and >> camera center point. Is your perceived difference greater toward the image >> edges? >> >> eetu. >> >> >> >> On 13.5.2013 16:36, Steve Newbold wrote: >> >>> Pixel perfect compared to what? A depth pass from the same render as >>> the world position pass? >>> >>> How far off are your values? Can it be put down to rounding of the >>> camera position from your 3D package or rounding on the pass values. Is >>> your depth pass 32bit float? Other things to check are premultiplcation >>> of the position pass from the renderer. >>> >>> Steve >>> >>> >>> On 13/05/13 14:26, Simon Björk wrote: >>> >>>> Hi all, >>>> >>>> I'm looking for a way to accurately converting a point position pass >>>> (world space) to a depth pass (camera space). I have a camera available. >>>> >>>> The following expression gets me close but not pixel perfect: >>>> >>>> set cut_paste_input [stack 0] >>>> version 7.0 v4 >>>> push $cut_paste_input >>>> Expression { >>>> temp_name0 cx >>>> temp_expr0 shot_camera.translate.x-r >>>> temp_name1 cy >>>> temp_expr1 shot_camera.translate.y-g >>>> temp_name2 cz >>>> temp_expr2 shot_camera.translate.z-b >>>> temp_name3 dist >>>> temp_expr3 sqrt(cx*cx+cy*cy+cz*cz) >>>> channel0 rgba >>>> expr0 dist >>>> channel1 none >>>> name Expression7 >>>> label "convert p world to z-depth" >>>> selected true >>>> xpos 266 >>>> ypos -50 >>>> } >>>> >>>> >>>> >>>> ______________________________**_________________ >>>> Nuke-users mailing list >>>> [email protected].**co.uk<[email protected]> >>>> ,http://forums.**thefoundry.co.uk/ <http://forums.thefoundry.co.uk/> >>>> http://support.thefoundry.co.**uk/cgi-bin/mailman/listinfo/**nuke-users<http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users> >>>> >>> >>> >>> >>> ______________________________**_________________ >>> Nuke-users mailing list >>> [email protected].**co.uk<[email protected]>, >>> http://forums.thefoundry.co.**uk/ <http://forums.thefoundry.co.uk/> >>> http://support.thefoundry.co.**uk/cgi-bin/mailman/listinfo/**nuke-users<http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users> >>> >>> >> ______________________________**_________________ >> Nuke-users mailing list >> [email protected].**co.uk<[email protected]>, >> http://forums.thefoundry.co.**uk/ <http://forums.thefoundry.co.uk/> >> http://support.thefoundry.co.**uk/cgi-bin/mailman/listinfo/**nuke-users<http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users> >> > > > _______________________________________________ > Nuke-users mailing list > [email protected], http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >
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