Green screen help

I have a video I'd like to graft an explosion into, and an already keyed explosion. How can I get rid of the black background, and then use the explosion in another clip?

Comments

  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff
    edited April 2012
    When you say you have an already keyed explosion, do you mean that you have keyed it in a separate comp shot from the footage you want to add it to? If so, then just select the layer containing the explosion, copy it, then paste it into the comp with the other footage, or add the entire explosion comp into the timeline containing the footage, and the key should be retained.
    I am wondering, though whether your explosion is actually pre-keyed, as I get the sense that the black background is still there, and has not in fact been keyed out yet. If this is the case, then change the Blend mode of the explosion to Add or Screen, to remove the black, and you'll be good to go. The blend mode is found in the Layer Properties.
  • My situation is: I have a video of my throwing something, and a clip I downloaded of an explosion. The explosion is on a green screen. How can I take this and make it an effect?
  • Froi
    Froi Posts: 966

    My situation is: I have a video of my throwing something, and a clip I downloaded of an explosion. The explosion is on a green screen. How can I take this and make it an effect?
    Just key out the greenscreen, and you will be left with a black background (when keyed in separate comp) then do what axel said :)
  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff
    So when you say the explosion is pre-keyed, you mean that you have already keyed out the green? Is the explosion in the same comp as the footage, or in a separate comp?
  • It's a different comp.
  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff
    edited April 2012
    OK, so my first post suggested two methods or working with that scenario; can you explain what goes wrong when you try those?
    You should be able to either add the explosion comp over your footage, or copy/paste the explosion layer over the background footage.
  • If the explosion appears over the scene with the black box, will the box go away.
  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff
    You can certainly remove the box. Is there something inside the Composite shot in addition to the explosion footage?
  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff
    Hm, if there is just a greenscreen clip in the composite, from which the greenscreen has been removed, then there shouldn't be any black box around it; the alpha created by the key should be baked into the comp. You can change the blend mode of the comp to Screen or Add to remove the black, but the question now is why is the black box there to begin with? Could you submit a suport question and attach the .hfp file so I can take a look?
    http://support.hitfilm.com/index.php?_m=tickets&_a=submit
  • I can't share the file, I can't afford the whole software, but to fix my problem I just dragged the explosion file(after I had keyed it)to be another layer for the video.