Sylvie/Supergirl Background Replacement

[Gary Kleiner]

The Chroma Keyer let’s you specify the range of color to key out.

Gary Kleiner

[Rickm1]

I’m aware of the fact that you can use the chromakeyer to key out a color. But I don’t see how he could have used that technique in this example. As I said, Sylvie was evidentally shot against a *white* background, and yet you could still see the whites of her eyes in the video that chanimal composited/produced. How could he have doen that?

And lets say for argument’s sake that he did indeed use just the chromakeyer. I thought you could only do that successfully if you shot the video against green or blue screen…?? As I stated in my original post, I shot my video against a black background (not by choice mind you). How could I chromakey out the black? I’ve tried that before and it makes the person partially transparent. I’m open to suggestions. Thanks.

[Peter Wright]

The principle behind chroma keying is that the background screen should be a colour that is not present on the subject – green or blue are the most commonly used, but any colour will do, as long as the subject doesn’t have that colour.

With Vegs 5 or 6, you can use Bezier masking, or a combination of Bezier masking and Chroma, but the beauty of Chroma is that you don’t have to draw round each frame as the subject moves.

Peter Wright
Perth, Western Oz
http://www.allroundvision.com.au

[Rickm1]

I understand the theory behind chomakeying, at least to the degree that you want to use green or blue screen, which is evenly lit, as the background. I also realize that you want the foreground object and background object lit separately and that you want the foreground object to be far enough away from the background so that he/she does not cast a shadow.

That being said, this still hasn’t answered my first question. As I said before, by all evidence, Sylvie was shot against *white* screen. I would really like to know how Chanimal composited it and replaced the white background. I would be surprised if he said it was by using a bezier mask as it’s quite a bit of video. Here is the link to the video so that those who are interested can take a look and maybe offer a suggestion as to how he did it:

https://www.vegasusers.com/vidshare/textdisp?chanimal-supergirl-stonefield

There is another link earlier in the forum that shows the *original* footage that was shot with sylvie against the white screen. I can post that link if you wish. -Rick

[Rick Dolishny]

Short answer is there are more than two layers.

A perfect key would involved only two layers: the top being the one you’re keying and the bottom your background.

In the case of this if you simply do a luminance key or chroma key out the white the whites of the eyes will be keyed as you pointed out, not the desired effect.

So you add another layer on top, this one is a sort of reverse garbage matte. You use Vegas 5’s bezier mask to coarsely mask out the key, leaving the edges of the model to be keyed out with the keyer. I typically have the middle layer (the one to be keyed) muted so I can see the results of my mask.

Now I use combustion and after effects for this sort of thing but I BELIEVE with Vegas’ parenting you can parent the two layers and add a colour correct to the top layer and it will ripple through to the siblings (as in Combustion).

Is that what you’re going for?

– Rick

[Peter Wright]

Thanks Rick – that’s what I meant by “combination of bezier & chroma” but you described it in much more detail!

– and Bezier masks have controllable soft edges so no-one sees the join

Peter Wright
Perth, Western Oz
http://www.allroundvision.com.au

[Rickm1]

Thank you, it sounds like this will put me on the right track. I wish I could get in contact with this Chanimal guy and ask him exactly he did it and with what software tool, but like I said, your post looks like it will send me in the right direction. Thanks for your help.

[Liam Kennedy]

Do a search for posts by Chanimal over on the Sony forum. Click on his “name” in the search results and you’ll get to his account profile… then click on his highlighted “name” aagin in his profile and you can submit a question directly to him.

[Rickm1]

Right on! Thank you, I’ll look him up.

[Rickm1]

Hey Rick,

Is Combustion a better tool than vegas for more control of chromakeying and/or compositing? I would like to get the best tool for this sort of thing. I have a copy of Pinnacle’s Commotion Pro 4.1 but haven’t learned how to use it yet.