Mocha Tips: How to Track Occluded Objects
Фильм және анимация
In this quick tip, Mary Poplin, Boris FX Product Specialist, will cover some Mocha tracking techniques to solve difficult shots: what to do when the object you are trying to track is partially or fully occluded, the importance of layer order, how to avoid occlusions, and how to spot occlusions before you start tracking. One of the most common problems in tracking occurs when foreground objects cover the object we are trying to track. We call these occlusions. For example, when a finger swipes across a phone or when actors pass in front of monitors we have a tracking occlusion to solve.
How to spot occlusions:
Most occlusions are obvious. Mocha is pretty smart about filtering texture, but it can get confused by moving objects, reflections, shadows, or people that slowly or barely move in front of the area you are trying to track. Mocha is smart enough to ignore most noise and quick inconsistencies like explosions and rain, but slow moving objects give mocha enough texture from one frame to another for mocha to get derailed. (Show explosion example, even though it is used before.
Partial Occlusions:
For partial occlusions, avoiding the occlusion can be as simple as tracking the object as normal and then pausing and moving the shape to another area moving in the same direction. Just keep in mind that animating a shape doesn't animate the track, it simply tells the track to look in a new location. Turn the surface tool on to see what your track is really doing.
Layer Order:
You can also use layer order to hold objects out of your track. Layers at the top of the layer pile are automatically held out of layers below them when tracking. Simply draw a shape around the offending object, and drag that layer to the top of the layer pile in layer properties. If you always track objects from the FG to the BG you will always have holdout shapes for your tracks below.
Full Occlusions:
When an object is not visible or entirely occluded, you can use manual track to jump past them. You will need to turn your surface tool on and then switch to manual track in the track tab, notice how the surface tool becomes a dotted line. Then you can hand keyframe any interruptions in the track. If this looks good, keep tracking forward. If not, track into the occlusion from either side of the timeline and delete any messy tracking keyframes by using the keyframe Minus - button.
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Пікірлер: 26
No other tutorial has mentioned the layer order trick before. That's a lifesaver, thank you!
@BorisFXco
Жыл бұрын
Glad it helped!
Thanks Mary! As always, you're simply the best instructor out there.
Excellent! Thank you Mary a lot 😊
Does the technique of tracking foreground objects so that they don't interfere only work in Mocha Pro? I've tried that in Mocha AE, and it doesn't seem to do anything. The moment the object starts to get eclipsed, everything starts to drift.
@BorisFXco
3 жыл бұрын
No, this works with all versions of Mocha. A good technique is to create loose track mattes first before you do the track on your main layer. Remember to turn off tracking on the track mattes with the cog. If you are still having trouble with this, hit up the forums (forum.borisfx.com) and post a screenshot of your setup or project if you can.
how do we mask out two roto layer from one tracking layer
great these is needed
@BorisFXco
4 жыл бұрын
Thanks, Rony!
@ronydey2696
4 жыл бұрын
@@BorisFXco MOST WELCOME SIR FROM THE BOTTOM OF MINE HEART❤
0:17 Why is Rich Evans there?
but how do i make it modify its mask so the mask of the objects changes based on what its ocluded of the object
@BorisFXco
2 жыл бұрын
If your shapes are correct, the tracker should pick up all the areas that aren't occluded. Check out this short video on track mattes : kzread.info/dash/bejne/nJyrkpqOqKzHYZs.html It is often necessary to create the mask for the occlusion first. Hopefully the video will explain it better than my comment.
i mean is that if unpper layer roto is for masking then if i add one more shape does the 3rd layer will do what ?
@BorisFXco
Жыл бұрын
All shapes will occlude all the layers below it. So Layer 2 will be a track matte for Layer 1. Layer 3 will be a track matte for layers 1 and 2.
Layer order did nothing for me, it still shows the image im trying to replace above the other layers that should be subtracted. How to fix?
@BorisFXco
Жыл бұрын
If you're doing this in Mocha Pro's Insert Module, remember to use the Masks are to mask out layers above in the render. If you're using this data in a different program afterwards, the easiest way is to duplicate the layer and use the Mocha mask to patch over the insert. Take a look at this video to show you a fuller workflow : borisfx.com/videos/introduction-to-mocha-ae-bundled-with-after-effects/
hi what about objects that go out of frame? there is an error message that comes up.
@BorisFXco
4 ай бұрын
Yes, when Mocha cannot get a confident track on a shape it will pop up an error message saying the tracking ending prematurely. You can then go back a few frames and tweak the shape, the parameters, or add a track matte, to help the tracker get a better result.
@OptimalMan101
4 ай бұрын
thank you@@BorisFXco
This isn't working on my Mocha. I put the layers in the correct order but the background layer still shifts.
@vinloc3854
3 жыл бұрын
Hey man, Boris FX is pretty good about helping people out but if you want I can lend a hand. I'm taking it you have something that you're trying to track and its not working, right? what is it? If need be we can meet on discord and trouble shoot. Let me know if you're interested.
@BorisFXco
3 жыл бұрын
You may need to make the track matte object (the one on top) a little bigger than you usually would if you were tracking it normally. Another thing to try is to delete all the old (bad) tracking data from the bottom layer before re-tracking it. Use the Dope Sheet for this.
Too fast and unusefull.
@BorisFXco
3 жыл бұрын
Check out Exercise 04b of Mocha Essentials for a slower run through of track mattes : borisfx.com/free-training/mocha-essentials/
@polloloco6353
3 жыл бұрын
@@BorisFXco Thanks.