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Activity Forums Adobe After Effects Expressions Fake Reflection problem

  • Fake Reflection problem

    Posted by Andrew Donaldson on December 16, 2011 at 11:20 am

    Hi guys, i posted a question over in the regular after effects forum on how to get realistic reflections and was pointed to this link:

    https://tv.adobe.com/watch/ask-the-adobe-ones/4-faking-reflections-in-after-effects-with-expressions/

    I am creating an iPad promo with an iPad floating around showing off all the features, etc.
    I am using a fake floor (its a BG that i supposed to look like a floor, so i don’t actually have a floor plane) which should be casting the reflection of the iPad.

    The above link was really helpful, but the wierd thing is that when the camera rotates to the right the reflection is fine, but when it dollys left the reflection is inverted! Its on the same plane(just the other direction) so the expression should be fine! no?

    Im really sorry if you don’t understand what im saying, but I’ll post an example here:

    https://vimeo.com/33775625
    It should be online 30 mins from now…

    I know its not perfect, but the first move i can deal with. The reflection goes the right way, etc. But the last move where it says ‘interactive pages’, the reflection is inverted!

    Still very new with expressions, so any help is very much appreciated!

    thanks guys!

    xp = thisComp.layer("FINAL iPAD COMP").transform.position[0]
    yp = thisComp.layer("FINAL iPAD COMP").transform.position[1]
    zp = thisComp.layer("FINAL iPAD COMP").transform.position[2]

    transform.position = [xp,(900+yp),zp]

    xo =thisComp.layer("FINAL iPAD COMP").transform.orientation[0]
    yo =thisComp.layer("FINAL iPAD COMP").transform.orientation[1]
    zo =thisComp.layer("FINAL iPAD COMP").transform.orientation[2]

    transform.orientation = [xo, yo, (0-zo)]

    Andrew Donaldson replied 14 years, 7 months ago 3 Members · 4 Replies
  • 4 Replies
  • Kevin Camp

    December 16, 2011 at 7:10 pm

    hi andrew, i had seen your post in the other forum, and thought about pointing you to this method for creating relfections:

    https://qubahq.com/2010/06/tutorial-100-accurate-reflections/

    but i thought darby’s solution would probably work for you. however since it didn’t seem to, you might check it out.

    it is a bit of a process, and it would involve changing your current setup — primarily hiding the current reflections and creating the reflection comp/camera set up, and then compositing the first comp and reflection comp together. but it really produces great reflections for any 3d layers.

    Kevin Camp
    Senior Designer
    KCPQ, KMYQ & KRCW

  • Andrew Donaldson

    December 18, 2011 at 4:49 pm

    Hi Kevin,

    Thanks for that, but its still not really what im looking for.

    The detail in the reflection is not really what i want. All the methods of casting reflections seem to be duplicates of the original comp that stick to the original. This isn’t realistic. because a real reflection is the opposite of the object being reflected.
    Ideally, when an item is lifted up away from the floor, the reflection moves in the opposite direction. But almost all the methods I come across make the reflection stick to the original.

    the method i used at the start of this post was pretty much spot on, apart from the weird axis thing i mentioned.

    Its still a little baffling, but i might have to either forget the reflection completely or hope no-one notices that the one camera move causes an opposite reflection.

    Thanks for taking the time to reply though.

    Andrew.

    ps, the link wasn’t in my original post:

    https://vimeo.com/33775625

  • Dan Ebberts

    December 18, 2011 at 5:47 pm

    I tried it with these versions and didn’t notice any problems with camera movement:

    // position

    pos = thisComp.layer(“FINAL iPAD COMP”).transform.position;
    transform.position = [pos[0],700-pos[1],pos[2]]

    // orientation

    orient = thisComp.layer(“FINAL iPAD COMP”).transform.orientation;
    [-orient[0], orient[1], -orient[2]]

    Dan

  • Andrew Donaldson

    December 19, 2011 at 10:15 am

    Hey Dan,

    Ive figured out what was going wrong.

    My camera was inside one of the precomps, and although I never really started out to have a camera nested inside a precomp, it just kinda evolved that way.
    I took a few minutes to re-jig the whole thing and the expression worked fine. I think it needed me to step back from it to sort it out.

    Thanks for your time.

    Andrew.

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