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Difficulty parenting layer to a track, need some coaching
I can do this job in Motion, but I’m new to AfterEffects, and I’m finding it less intuitive how to get this done, need some coaching:
I have a video layer that’s been shot with a fixed but tilting camera, I’ve tracked that shot with the point tracker, and made a null object track. I’ve also made a mask on the original track to cut out the extraneous parts of the set, and I have a png file of a cave or tunnel to replace that. Actress battles her way forward thru the file cabinets to foreground, camera mask subtle tilt down to keep her in frame. At some point I also have to key out that green as well. The perspective on the cave walls is of a bit and I’ll need to warp that into a better look later…
Where I’m stuck now is in the step-by-step of connecting the tracking to the null, and connecting the mask and the new background to that null. I confess I’ve been stumbling around the interface and while this is pretty basic AE stuff, I’m frustrated. I’m stuck at the step of parenting the mask layer and parenting the “walls” layer to that null. Someone with patience, can you please walk me thru what’s next?
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15 Replies
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In your tracker window you need to hit EDIT TARGET. then choose your null, then apply…you have the motion data applied to the clip itself which is no help for anything
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Did that, but the mask does not follow the null…
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The mask layer has no controls or way to connect the pickwhip to it. I’m not very good at this GUI.
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To say it another way:
Masks are attached to the solids they are drawn on. To move a mask the way you want, you have to move the whole solid – the mask will come along with it. You do this by either parenting the solid to the tracked object or by sending the tracking data to the solid that has the mask, as Richard suggested. Then use the solid/mask layer as a cookie cutter to have your video shine through (this is the track-matte every one is talking about – I know it’s not the best name). The video goes below the solid layer (with the mask) and you choose “Alpha Matte” from the TrkMat column on the video layer.If you send the tracking data to the solid/mask layer you may need to reposition it. You can adjust the solid’s anchor point to get the mask back where to need it. It will then follow the tracking point around properly. If there is some perspective change you could put the solid with the mask in 3D and tilt it slightly (rotate in the X) to better match your camera angle.
You could move the mask around on its own but you would have to keyframe the maskpath attribute and if you already have track data, there’s no point in doing it the hard way.
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I’m unclear in how to get the drawn mask off the source and into the solid
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Don’t need to. You can just duplicate the source and you will have two, each with a mask. Turn off the mask on source1 and use source 2 as the masking layer linked to the track.
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can you use mocha..if you draw your mask in mocha and track forward you would get a very sturdy mask
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If you really must move the mask, you can just copy and paste it from one layer to another. But the two layers must have the same dimensions or the mask will distort.
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I’m a bigger noob in mocha than in AE and isn’t mocha a planar tracker, when I believe this is a job fora point tracker? I need a lot of RTFM on this, to be sure.
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when you click the video layer and hit M to bring up the masks. Click down on the arrow to see the Mask path and feather and other options.
To get the mask path to a solid layer all you have to do is select the mask path property from the video and copy it. Then make a solid layer and just paste onto the solid and you should see that mask pop up. Now you can use the solid as a matte for the video track.
Just make sure it’s right on top of the video layer in the layers panel. You should see the option to set a track matte on the right half of the layer panel next to the blend mode drop downs. You may have to turn on the mode column if you don’t see it up already.
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