Gary, Just worked on a project that involved using CG velocity and depth channels... You can use the velocity channels, depth channel and a VectorBlur node to control post-render motion blur quite nicely.
Depending on what program generates the velocity channels, you may have to swap the channels around a bit to get the u and v motion channels (analogous to x and y) in the right place. The offset and multiply values in the VectorBlur node will likely need to be adjusted to get the right amount of blur desired. And, you may need to turn on the mask and use the alpha to limit what you’re blurring. For example, I was motion blurring fire, rendered on black, out of Fume. I used a shuffle node to copy the red and green channels from the velocity layer into a new layer in Nuke with x and y channels (for my own sanity), which I selected in the VectorBlur node’s "uv channels". I used the inverted alpha as a mask and ended up having to crank the multiply value up to 40 to get the amount of blur I wanted. I also had an Alembic file with the original camera used for the render. I fed that to a MotionBlur3D node, along with the depth channel, which generated the uv motion channels and then used a VectorBlur node to add camera blur to the whole scene. Using the depth channel in conjunction with the motion vectors allows for a more correct approximation of “real” rendered camera blur. Rich Rich Bobo Senior VFX Compositor Armstrong-White http://armstrong-white.com/ Email: richb...@mac.com Mobile: (248) 840-2665 Web: http://richbobo.com/ "Man does not live by a turkey in every oven or a color TV set in every home. Man lives by faith and hope and love, by the star on the horizon, by the trumpet that will not call retreat." - E. Merrill Root On Dec 26, 2013, at 1:48 PM, Gary Jaeger <g...@corestudio.com> wrote: > Sorry. I guess that was vague. I mean using velocity and zDepth channels on > CG renders > > On Dec 26, 2013, at 10:45 AM, Ron Ganbar <ron...@gmail.com> wrote: > >> Elaborate please? >> Do you mean on live footage? On CG? >> >> >> >> Ron Ganbar >> email: ron...@gmail.com >> tel: +44 (0)7968 007 309 [UK] >> +972 (0)54 255 9765 [Israel] >> url: http://ronganbar.wordpress.com/ >> >> >> On Thu, Dec 26, 2013 at 8:41 PM, Gary Jaeger <g...@corestudio.com> wrote: >> I know it’s a common question, but I’m curious if there are any tricks to do >> both in post? >> >> Gary Jaeger // Core Studio >> 249 Princeton Avenue >> Half Moon Bay, CA 94019 >> 650 728 7060 >> http://corestudio.com >> >> >> _______________________________________________ >> 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 > > Gary Jaeger // Core Studio > 249 Princeton Avenue > Half Moon Bay, CA 94019 > 650 728 7060 > http://corestudio.com > > _______________________________________________ > 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
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