Question about masking.

I made a green screen of just some character doing a walking animation. What I'm planning to do is have him go behind trees and other objects. Is it possible to create a mask for the character and move the layer around without the mask moving with the layer? Basically just have the mask locked in place and move around the layer anywhere without the mask following it. Is that possible?

Comments

  • Triem23
    Triem23 Posts: 20,069 Ambassador

    I'm confused. Are you asking about masking the background layer or the greenscreened walk cycle. 

    In short, masks lock to the layer, always. You have two choices here: you can animate the mask position to move around inside the layer, or you can create a MATTE.

    A mask draws a shape directly on a layer to define transparent areas. A matte uses transparency or color data from "Layer X" to define transparent areas on "Layer Y." this allows independent movement between the matte and bg layer. Set Matte effect  

  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff

    Or the third choice: duplicate the background layer, mask it so only the trees and other objects that need to be in front of the character are visible, and place it above your character layer.

  • VOKZEL
    VOKZEL Posts: 6
    edited November 2018

    Replying to Triem, I was talking about the green screen layer. What I meant by "locking the mask" is locking it in it's location. Go in Hitfilm and put a mask around something, then move that layer. The mask follows the thing you originally put it around. I want it to stay where it is. For example, get a paper and cut a hole in it, then put some picture behind the paper. Imagine the hole in the paper being the mask. Hold the paper in place and move the picture. That's what I want to happen.

    Replying to Axel, I guess I could do that. It would take a bit longer but it's probably quicker than waiting for a possible answer.

  • Triem23
    Triem23 Posts: 20,069 Ambassador
    edited November 2018

    @Vokzel nope, you want Set Matte. Incidentally, the same answer to your text question, so you have a video already.

    So. Key your walk cycle. Right-click and convert to a Composite Shot (move the effect). Your pre-keyed walk cycle is now an alpha matte source for a Set Matte effect.

    Edit: Oops, it's not your text question. 

    Watch the two videos in this thread. They will teach you the Set Matte effect. It's easier than moving the mask around. 

  • AxelWilkinson
    AxelWilkinson Posts: 5,252 Staff

    Using your illustration, the hole that represents your mask is not on the same layer as the picture. It works exactly the same in HitFilm. If you take a paper with a picture on it, and cut a hole in that paper, then when you move the paper the hole will also move. If you want the hole to stay in place, it must be on a separate layer, using either of the two methods Triem23 mentioned, or the third option I mentioned. Any of them will produce the result you want.

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