Using Matte Clip to Subtract

Ordinarily when I want a layer to subtract from my track, it’s relatively straightforward. I create a spline, track it, and set they blend mode to “Subtract”. Then under it I create a my tracking layer, set to “Add” and track away. At this point, viewing the mattes with the tracking spline selected shows a red area that is being tracked and a transparent “hole” where the subtraction spline is knocking out the area I don’t want to track. Simple.
However, sometimes I’d like to replace the subtraction spline with a video layer generated from After Effects. When I try this I do the same steps except I set the “Matte Clip” of the subtraction layer to my AE-generated matte.
Unfortunately, the results are not what I’d expect, and I can’t figure out how to make it work properly. Often the subtraction mask comes up purple or gold, and the add spline stops showing up when I view mattes.
Put simply, what steps do I need to take to use a video layer as a matte to knock out areas that I don’t want to track? Thanks for your help!
Cheers,
Ari

Thanks for your help Mary! So if I’m doing it correctly, and I have selected “mattes” in the view controls, and have the layer I wish to track selected in the layer controls, what should I see?

Thanks for your help Mary! So if I’m doing it correctly, and I have selected “mattes” in the view controls, and have the layer I wish to track selected in the layer controls, what should I see?

Ordinarily when I want a layer to subtract from my track, it’s relatively straightforward. I create a spline, track it, and set they blend mode to “Subtract”. Then under it I create a my tracking layer, set to “Add” and track away. At this point, viewing the mattes with the tracking spline selected shows a red area that is being tracked and a transparent “hole” where the subtraction spline is knocking out the area I don’t want to track. Simple.

However, sometimes I’d like to replace the subtraction spline with a video layer generated from After Effects. When I try this I do the same steps except I set the “Matte Clip” of the subtraction layer to my AE-generated matte.

Unfortunately, the results are not what I’d expect, and I can’t figure out how to make it work properly. Often the subtraction mask comes up purple or gold, and the add spline stops showing up when I view mattes.

Put simply, what steps do I need to take to use a video layer as a matte to knock out areas that I don’t want to track? Thanks for your help!

Cheers,
Ari

Hi, back at it again, and once again having trouble with Matte Clips. This time I’ve got the matte clip loaded into the top-most layer.
Clicking on the Matte layer yields a red overlay where the JPEG sequence is white, and transparent where it is black.
Once I set up a tracking layer under the Matte and hit track, the tracking layer does not track and remains stationary until a few frames after it begins to be occluded by the matte. At that point the track terminates with the error “One or more selections were not tracked properly. The images are too dark or not similar enough to track.”

Hi, back at it again, and once again having trouble with Matte Clips. This time I’ve got the matte clip loaded into the top-most layer.

Clicking on the Matte layer yields a red overlay where the JPEG sequence is white, and transparent where it is black.

Once I set up a tracking layer under the Matte and hit track, the tracking layer does not track and remains stationary until a few frames after it begins to be occluded by the matte. At that point the track terminates with the error “One or more selections were not tracked properly. The images are too dark or not similar enough to track.”

In mocha, you don’t need to set layers as add and subtract necessarily to exclude objects from the track, you can do that simply with layer order. Layers above one another will hold out as you track.
If you want to use an AE matte, or other rendered matte, simply render out a black and white JPEG image sequence or quicktime. Create a new layer in mocha and set the matte clip to your image sequence and arrange the layer on top of the layer(s) you want to hold that shape out of. You will now hold that area out of your tracks.
Think of mocha tracking as tracking from the foreground to the background, with objects closest to the camera at the top of the layer pile, and objects farthest from the camera at the bottom of the layer pile, you’ll end up holding out your foreground shapes from your background shapes and helping your workflow go faster.
Let me know if you have any questions!
Cheers,
Mary

In mocha, you don’t need to set layers as add and subtract necessarily to exclude objects from the track, you can do that simply with layer order. Layers above one another will hold out as you track.

If you want to use an AE matte, or other rendered matte, simply render out a black and white JPEG image sequence or quicktime. Create a new layer in mocha and set the matte clip to your image sequence and arrange the layer on top of the layer(s) you want to hold that shape out of. You will now hold that area out of your tracks.

Think of mocha tracking as tracking from the foreground to the background, with objects closest to the camera at the top of the layer pile, and objects farthest from the camera at the bottom of the layer pile, you’ll end up holding out your foreground shapes from your background shapes and helping your workflow go faster.

Let me know if you have any questions!

Cheers,
Mary

If you have loaded the black and white mattes into the “matte clip” area of the “layer controls” for the new layer (you’ll need to draw any shape to make a new layer, I recommend a 4 point shape) you should see the mattes in red on that layer.
If you have not loaded in a matte clip, you wont see anything.

If you have loaded the black and white mattes into the “matte clip” area of the “layer controls” for the new layer (you’ll need to draw any shape to make a new layer, I recommend a 4 point shape) you should see the mattes in red on that layer.

If you have not loaded in a matte clip, you wont see anything.

That sounds like a problem with the area you are trying to track, not the matte clip, but it’s hard to tell without seeing the shot.

Can you include a screenshot or can we do a skype screenshare to get to the bottom of this?

My name is mary.poplin on Skype.

Cheers,
Mary

That sounds like a problem with the area you are trying to track, not the matte clip, but it’s hard to tell without seeing the shot.
Can you include a screenshot or can we do a skype screenshare to get to the bottom of this?
My name is mary.poplin on Skype.
Cheers,
Mary