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Thread: Depth buffer & DOF effect problem

  1. #1
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    Depth buffer & DOF effect problem

    Hello!

    I have a little problem with blurring images in after effects. See this first image:

    Click image for larger version. 

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    There is a ball rendered with alpha channel. Now it is on After effetcs, so we see the background too.

    Together with a background it looks like this:
    Click image for larger version. 

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    Then we bring in the DETPH buffer render:
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    Now I use After Effetcs Lens blur effect and I setup the source to be correctly the depth buffer render (luminance), we got this:
    Click image for larger version. 

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    There are visible seams around the ball. It looks horrible cos there is the alpha channel transparency in the ball. The DOF effect made this way does not work..

    I have to use just normal gaussian blur in after effects:
    Click image for larger version. 

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    SO do enybody know how can I use this Depth buffer + Lens blur in after effects with images rendered with alpha channel?

    Pekka Varis

  2. #2
    I've had issues with edges of the depth pass in lightwave too. Try this workaround:
    https://www.youtube.com/watch?v=KiwJGWVEnME

  3. #3
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    What file type are you rendering to?

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    Thank you. I watched this but it does not solve my problem..

  5. #5
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    I am rendering to PSD+Alpha channel and Depth buffer is rendered to png. This works technically ok for after effetcs Lens blur. but After Effetcs does not blur the key'ed image. Insteadt it blurs the whole image and this leads to stupid looking seams in out of focus areas. It seems to be that if I want to use DOF effect in After Effects with depth buffer renders; I need to work with full size renders out of lightwave, so I need to compose everything or as much as possible in lightwave and not rendered out images with aplha channel.. Am I correct?

  6. #6
    Angry Mac User Otterman's Avatar
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    Render your Alpha on a separate pass. And render out with 32bit EXR! Should give you better results.
    Last edited by Otterman; 02-27-2018 at 02:38 AM.

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    Gotta try this! Thanks Otterman

  8. #8
    Hi Pekka, might need to interpret you image sequence to match your alpha settings. Maybe Pre-multiplied to black?

    I tend to use Alpha "Straight / Unpremultiplied" in Lightwave and Interpret as Straight in After Effects to avoid dark fringing.

    A few other things might be:

    Inverting the Depth map (White: Close, Black: Far)
    Gamma correcting the Depth map
    Ignoring Depth Alpha

    These adjustments will need to be pre-comped for the lens blur effect to see the changes.
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  9. #9
    You might want to try also a focus depth pass.



    More info here:

    http://forums.newtek.com/showthread....=1#post1301589

    A custom focus pass can be got in LW in this way as well:

    https://web.archive.org/web/20140617...ors#Focus_Pass

    In extreme cases like your example, you may want to render multilayers to keep background geometry data or mix 3D DOF with post-DOF.



    Gerardo

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    Quote Originally Posted by gerardstrada View Post
    You might want to try also a focus depth pass.



    More info here:

    http://forums.newtek.com/showthread....=1#post1301589

    A custom focus pass can be got in LW in this way as well:

    https://web.archive.org/web/20140617...ors#Focus_Pass

    In extreme cases like your example, you may want to render multilayers to keep background geometry data or mix 3D DOF with post-DOF.



    Gerardo
    oh cool. gerardo, would you feel comfortable putting some of this old stuff you have written into the extras section of the lw docs? there’s just so much excellent material you have written over the years and a fair bit got lost in the newtek forum explosion

    a gerardo section.

  11. #11
    Angry Mac User Otterman's Avatar
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    Quote Originally Posted by gar26lw View Post
    oh cool. gerardo, would you feel comfortable putting some of this old stuff you have written into the extras section of the lw docs? there’s just so much excellent material you have written over the years and a fair bit got lost in the newtek forum explosion

    a gerardo section.
    I second this. Gerardo's knowledge on sweating passes for post rocks!

  12. #12
    Quote Originally Posted by gar26lw
    oh cool. gerardo, would you feel comfortable putting some of this old stuff you have written into the extras section of the lw docs?
    Quote Originally Posted by Otterman
    I second this.
    Glad you find it useful!
    If they also think it's useful, they can use them of course!



    Gerardo

    p.s. the linked article was one of a series of 3 articles about the experimental use of node editors, but the other two were not possible due to magazine closing. A lot of things we can make with DP Node Editors...

  13. #13
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    Quote Originally Posted by gerardstrada View Post
    Glad you find it useful!
    If they also think it's useful, they can use them of course!



    Gerardo

    p.s. the linked article was one of a series of 3 articles about the experimental use of node editors, but the other two were not possible due to magazine closing. A lot of things we can make with DP Node Editors...
    oh i remember that. i had a subscription specifically for your articles and it was cut off. would you consider posting the missing two.

    the info you post is fantastic and the best resource on this forum. i asked beevee about a docs section. i think he is keen.

  14. #14
    Quote Originally Posted by gar26lw View Post
    would you consider posting the missing two.
    I never finished those articles but I will probably do after finishing another related to proper color flow.

    Quote Originally Posted by gar26lw View Post
    i asked beevee about a docs section. i think he is keen.
    Sounds GREAT! much appreciated, Thanks!



    Gerardo

  15. #15
    Super Member inkpen3d's Avatar
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    Don't anti-alias the Depth pass!

    If possible, render the Depth pass out at a higher resolution (e.g. x2, or x4) and scale it down in the compositing application (that is, if the comp application doesn't have resolution independent capabilities).

    If you AA the depth pass then you will end up interpolating the depth information of background objects (or the background itself) with the depth information at the edges of foreground objects . These incorrectly interpolated pixels will be set to intermediate depth values and, when brought into a compositing application and used with effects that utilise the depth information, will result in fringing around the foreground objects.

    Hope that helps,
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