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Activity Forums Adobe After Effects Expressions a tough one involving 3d channels and depth of field…

  • a tough one involving 3d channels and depth of field…

    Posted by Joe Carusoe on August 23, 2005 at 7:17 am

    i’m compositing some layers of a 3d render from maya. i can apply the depth of field filter in ae to the depth channel layer or an RLA file… but how do i transfer depth info to an entire composite?
    as in, use one layer as the depth of field Z information, then apply that to another composition?
    is this even possible?

    Filip Vandueren replied 18 years, 10 months ago 2 Members · 3 Replies
  • 3 Replies
  • Filip Vandueren

    August 23, 2005 at 4:24 pm

    As a workaround::

    you can extract the Z-depth to greyscale values, precompose that and feed it into a filter that uses greyscales to Blur selectively.
    There’s a third party-filter somewhere called Rack-focus that does that.
    I’m sure there are some Lensblur filters out there with the same functionality

    After Effects comes with ‘Compound blur’, which does not use a “centered Focus point” like rack focus, it always blurs 0 pixels at black, max pixels at white (or vice versa), but you cannot say : “don’t blur at 50% grey, but do blur at 0% black and 100% white”

    The workaround for that would be to create a “solarized’ greyscale map.
    I’ve created an example-project that does that, with two depth matte filters, and a channel combiner to turn the alpha-matte into a greyscale.

    It uses a few sliders and expressions to make the process easier to control, but they’re not really necessary.
    You get sliders for “Focal Plane”, “Focal Thickness” and “Focal plane feather”

    download the comp at:

  • Joe Carusoe

    August 23, 2005 at 5:21 pm

    hey, thanks for the reply and the files!
    i’m glad someone knows what i’m trying to.

  • Filip Vandueren

    August 23, 2005 at 10:39 pm

    Let me know how it went or if you have other problems.

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