Masking Around Green Screen For Starfield

J.R. Hudson

J.R. Hudson

Spirit Animal
Is it possible to MASK off everything around the GREEN SCREEN? I want to put in a starfield that sorrounds the entire frame and ship. This is John here, so I need dumbass terms. I tried masking and was succesful, but could not get my star field to fill the entire void.


dvxfal4nj.jpg
 
John,
If your camera isn't moving, cut a hole in some green screen paper. Set it up so you're shooting through the hole and masking everything else out; light it so the density of the green matches your ship BG. Old trick...works great.
I see dolly tracks in your picture....if you are moving in, you'll have to "float the "garbage matte" green screen so that the hole covers the same area on the move. Tricky, but it can be done. :)
Hope this helps.
Ken
 
John, I just played around a bit and put a bezier mask around your chroma screen, then used the CK in Vegas to eliminate the rest of the BG. Excuse the cheesy starfield BG, I just took the first thing I could find.

Starfield.jpg
 
Unfortunately, Bezier masks aren't available in V4.

I assume you're intending to move into the model on the dolly track, which would in any case require a keyframed garbage mask. You can make one in Microsoft Paint (black where you want the mask; white where you want it to show through) and then set up a parent/child compositing relationship between the mask track (upper) and your video track (lower). You'd export a number of stills which handles the changing size of the mask and make them into a traveling mask animation. Go as broad as you can (which isn't much at first if you're going to star that far out) so that you only have to step up to a wider mask as few times as possible.

Then you can chromakey out the green.

I made this garbage mask up quickly, but you can see what would need to be done afterward:

dvxfal4nj4ww.gif
http://img27.exs.cx/img27/1729/dvxfal4nj4ww.gif
 
You know what? Scratch all that. Like a zealous engineer, I'm trying to create a too-elegant solution when simplicity will do.

You can just keyframe a normal CROP to that rectangular shape, making it bigger as your need increases. Use the greenscreen as your guide.
 
Thnaks guys for the replies.

David, are you saying use a PAN/CROP the track with the actual Greenscreen? Then Keyframe as needed using the GREEENSCREEN as my guide? I'll try this now; thank you.

I see what you are saying David; but when I move to CROP it is BLOWING THE IMAGE up; what am I missing? :cry: :lipsrseal :undecided

YEs, I know I need V5 or V6 :P
 
You need to disable a couple of things: you don’t want to preserve the aspect ratio and you don’t want to size about the center. You need a free hand here.

Then, as the greenscreen gets bigger in your image (as you dolly forward), adjust and keyframe the crop as needed.
 
What you want to do is called a "garbage matte", although I doubt Vegas 4 calls it that.

You can just crop it down and then adjust the "stretch to fill window" parameters to make sure that it doesn't resize your image. Anything you crop off will become completely transparent.

*edit: DOH! David beat me to it!
 
That's the part I am missing Barry; I am not sure how to adjust the PAN/CROp without it ZOOMING in. Where is the feature/button?

Sorry guys; first time doing Greenscreen ever. Usually only use PAN/CROP for 4:3 to Letterbox adjustment.
 
Look at the buttons along the left edge of the pan/crop window. One is for size about center; one is for preserve aspect ratio. You want to unclick both.

Unfortunately, I'm used to V5's window now and I don't remember if there are any differences between the two off the top of my head -- those should be the same, though. Give it a shot.
 
Agggh.

It's not working; I Crop around Green and it's zooming everything. What the...?!

When the top is brought down it stays where I want; the moment I bring the left and right sides in it ZOOMS.
 
LOL

OMG

I am; I swear; it's still doing it. I'm not trying to be thick headed here guys. I'm doing as mentioned and its ZOOMING in.

I select Pan/Crop
I unclick: LOCK ASPECT and SIZE ABOUT

If I adjust TOP and BOTTOM only it stays the same - But zooms when I adjust the LEFT and RIGHT

If I adjust LEFT and RIGHT it stays the same - But zooms when I adjust the TOP and BOTTOM

Arrrgghh!!!!!!!!!!!!!!!!!
 
I don't think you want to use the crop function. In my mind that would be literally cropping your footage. You need to mask off the areas not covered by the greenscreen and animate that mask as you dolly in.
 
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