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TUTORIAL: G Matte: Simple cloning with split screen

Posted: Thu, 15th Apr 2004, 2:27pm

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Simon K Jones

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Chromanator tutorial: Garbage mattes

Simple cloning with split screen

In this project I'll show an example of how to achieve 'cloning', whereby you can use the same actors/props to portray multiple subjects in the same shot. I'll use these three separate shots:

1. 2.

3.

  1. Two marines and the hero character in the centre.
  2. An isolated marine on the left of the frame.
  3. An isolated marine on the right of the frame.
  • Clip 1 can remain as it is, and will form the base of the shot.
  • Clips 2 and 3 will be composited on top of Clip 1.
  • Therefore Clip 1 should be on Track 1, Clip 2 on Track 2 and Clip 3 on Track 3.

First I will set up Clip 2 by switching to the Object View to access the tools. Clicking on the Key tab and then the Garbage Matte tab accesses the correct toolset. It is important that the garbage matte includes the shadow that the marine is casting on the blue barrel just behind him, which will result in a matte that looks a little like this:

It is easier in this case to draw the mask freehand (instead of clicking each individual point).

  • The mask is closed by drawing back onto the first point. Changing to the Animate mode locks the shape.
  • Turn the Invert Matte option On to exclude everything except the selected area.

That's one marine taken care of. The marine in Clip 3 is a little trickier, as his shadow on the right-hand barrel needs to be included, but an all-inclusive shape won't work, due to the other marine that stands between the actor and the barrel. I could draw an awkward shape that goes off the bottom of the frame, then loops round to include both the marine and the barrel, but there is a neater solution.

Switching to Clip 3, I add a new section with the button and draw around the right-hand barrel. After closing and locking the shape, I turn the Invert Matte option On. This excludes everything except the barrel.

Of course, I don't want it to exclude the marine as well, so I'll create another section and set it up to add the marine back into the shot.

A new section can be added with the button and I can then draw a simple shape around the marine.

  • After locking the shape I now change Transparent Matte to Opaque Matte, which means that the marine will be included in the shot once more.
  • Ensure that the Invert Matte is turned Off.

The Transparent/Opaque Matte option can prove very useful when making complex composites.

  • A Transparent Matte will remove the selection from the shot.
  • An Opaque Matte will add the selection back to the shot.
  • The 'selection' is always the red area.

If lighting differences highlight the shape of the matte, feathering can be used to blur the edges. These two simple garbage mattes will result in a perfect composite, which an audience would never even guess was a special effect:

Taking the next step
This is just making simple use of garbage mattes. As Chromanator can handle garbage mattes that consist of several multi-point masks, things can get as complex and precise as you require.


Posted: Sat, 25th Dec 2004, 12:21pm

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Erfa

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Perfect tutorial. I will start making clones of myself at once...
Posted: Sat, 25th Dec 2004, 12:28pm

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Klut

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Basic and very good, I've used this alot.
Posted: Mon, 14th Feb 2005, 2:19am

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TimmyD

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Is there a maximum number of masks you can use?
Posted: Mon, 14th Feb 2005, 5:44am

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Hendo

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timmyd,

The maximum appears to be 20 mask 'sections' per object.

The exact message from the application is:
"You can only have a maximum of 20 sections in a single mask/garbagge matte."

But you could place multiple mask objects onto your timeline and then create up to 20 mask sections within each object.

Hendo
Posted: Mon, 14th Feb 2005, 9:04pm

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TimmyD

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I meant a max. number of masks you can create.
Posted: Thu, 24th Feb 2005, 1:18am

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hatsoff2halford

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So with this do we have to go through eavh frame and see what the actors effect with like shadows and keep making garbage mattes?
Posted: Thu, 24th Feb 2005, 3:49pm

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TimmyD

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hatsoff2halford wrote:

So with this do we have to go through eavh frame and see what the actors effect with like shadows and keep making garbage mattes?
Could you please rephrase that?
Posted: Fri, 25th Feb 2005, 1:16am

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hatsoff2halford

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So lets say the actor i want to clone moves around a lot, does that mean i have to follow him every frame and see if I need to make another garbage matte around him to have him show through?
Posted: Fri, 25th Feb 2005, 4:03am

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Arktic

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You don't have to draw a new g/matte, just use Chromanator's animation feature to animate the mask around the character. However, if the motion is particularly complex, then yes, you're likely to end up doing the whole thing practically frame by frame.

But you might also want to consider using chromakey in order to reduce the ammount of time you spend g/matting a subject to replace them in a shot. It will take more time to match the lighting and such, but it can prove to be very effective.

Hope this helps smile

Cheers,
Arktic.
Posted: Fri, 13th Apr 2007, 8:18pm

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The Editing Room

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that tutorial is extremely helpful. I have made a few vids today with cloning and my first is surprisingly good...