This area of the screen is not moving.  See the problem area below...the background is bleeding through.  First, is there a way to reshoot to eliminate this undesirable artifact?  My green screen is fairly well lit.

I was hoping that I could mask off this area as shown in the polygon area below

I hope that helps explain my problem!

Sorry, but I can't make out what you mean from those very low res screnshots.

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Terry, East Grinstead, UK

Hi

It is possible to create a mask from the green screen footage (depending on the clip contents), and use this to mask out the parts you want - this also works for where the subject is moving.

Create the mask as follows:-

1. Put the green screen video on the timeline.
    
2. Apply Chroma key and adjust Threshold and Fading range to reduce green fringing to a minimum
    
3. Adjust the Brightness to 100 and Contrast to 0
    
4. Go back to the Chroma key effect and adjust the Threshold and Fading range settings to get as near pure black and white mask as possible
    
5. Export the mask as a MXV file using the same resolution as the green screen clip.

To use the mask set up your timeline as follows

1. Remove all effects from the green screen clip
    
2. Import your mask and background setting the clip order as shown below
    
3. Apply Chroma key Alpha to the mask and adjust the direction (arrow appears near beginning of the mask when you hover the mouse over it
    
4. Depending on the subject you may  need to apply the Chroma key effect to the green screen video - in the sample i used this whas not necessary

HTH

John

Hi,

Here is another way, quick and dirty, especially if the zone to be protected can be covered easily by an existing mask.

I created a green screen image as a green rectangle, with a blue circle in the middle and a green triangle in the middle of the circle. The background is redish, one of the MEP backgrounds. The object is to show the blue circle and the green triangle on the redish background.

Original image:

Place background on track 1, image above on track 2, copy it to track 4. Chromakey green the image on track 2.

Bring in a hard mask, preferable no gradation, just black and white, with a shape that will be able to cover the triangle or zone to be protected. Note, bring this in as an object, not as an effect. Place it on track 3. Chromakey Alpha on the mask. Depending on which type you brought in, you may have to invert the chromakey arrow on the object. We want white to protect the zone. Resize the mask to cover the zone to be protected, that is, in my case, the white circle.

Next image shows green screen on red background. Triangle is unprotected, thus is redish. We want green.

Next image shows the mask added. You can see the black circle (which is really white) covers the triangle that we want to protect.

Lastly, the next image show the combination of all 4. Et voila, the green triangle is protected.

If you have trouble with the masks that you have, create one that is more suitable.

I like John Baker's solution for the complicated ones.

HTH

Hi,

Here is another way, quick and dirty, especially if the zone to be protected can be covered easily by an existing mask.

A mask you would need for your shape, could very easily be created within MEP by placing a black swatch in track 3 and using the 3D distortion effect to shape it to fit the perspective/shape of the circuit board.

You could probably even animate it by saving it in the masks folder and using "attach object to a position in the video" command.

Ss

My contribution, building on what the others have said.

Here's the mask of your circuit board.
https://dl.dropboxusercontent.com/u/4019461/CB-MaskWhtOnBlk-Alpha.bmp

Or for better quality:
https://dl.dropboxusercontent.com/u/4019461/MEP-GreenScreenProtect-1.jpg

Or for better quality (and typo correction!):
https://dl.dropboxusercontent.com/u/4019461/MEP-GreenScreenProtect-2.jpg

Or for better quality:
https://dl.dropboxusercontent.com/u/4019461/MEP-GreenScreenProtect-3.jpg

Or for better quality:
https://dl.dropboxusercontent.com/u/4019461/MEP-GreenScreenProtect-5.jpg

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Terry, East Grinstead, UK

Thanks for the help everyone!  I started trying a few of these techniques.