How to stop green screen virtual background from moving

Hello!

Total newbie here, I am a Dad whose 12 yr old kiddo and 10 school friends decided to write and make a star-wars-y movie. Last summer we filmed the first one (7 minutes, plus 7 minute hilarious bloopers), now we are filming the sequel (about 45 min), a year later with the kids growing up, amazing to see.

I am the designated cameraman (iPhone) and editor (iMovie, now learning HitFilm). Sadly for the kiddos, I am not very good at all.

I film against a green screen, in order to add space backdrops etc in editing.

If I pan the camera when filming against the green screen, then the virtual backdrop "moves" as well in playback, making the whole scene wobbly and dizzying.

How can I have the virtual backdrop "move" correctly when I pan the camera when filming against the green screen?

I don't even know the correct terms to use here (I don't think it is motion capture or chroma) and apologize to you all for this.

The only thing I can think of doing is .. not pan when filming and do multiple cuts from different angles. But some scenes would be good with a pan!

Finally, there is almost no budget (left) to buy any expensive s/w or app etc. Maybe for the third sequel.

Help!

Thank you to whoever read this to the end!

Answers

  • Stargazer54
    Stargazer54 Posts: 3,889 Ambassador

    @Dad_Trying2 Posting a video example of your issue might help us see what you are trying to do. I can only guess that your green screen only covers a small area and when you pan the camera you are panning away from the green screen?

    A possible solution would be to motion track something in the shot and attach a green background to that along with a mask to only reveal the areas of interest. This could be done in one composite shot. Then bring that comp into a new comp and perform the green screen key. All easier said than done.

    Might be a good idea to do some research online for green screen and traveling matte or mask. Here is one I found by searching for "greenscreen traveling mask camera pan". The demonstration on adding the mask is at about 5:10 but all the information about adjusting your key prior to that is useful (Even though this is a Final Cut tutorial you should be able to apply that to HF.)

    That will get you a mask that you can then attach to a track. In the tutorial below I talk about how to attach the mask to tracking data and also adjust its shape over time.

    While these videos don't directly address what you are trying to do you should be able to pick up the concepts and apply them to your project.