Regarding linking roto shapes to a track


In mocha documentation there is one tip regarding rotoscoping:


While you can refine a shape you have tracked to do your rotoscoping, the recommended way is to do a rough shape to track something and then link your roto to that track.

I used this method to roto a passenger bus passing by and it worked very well. But I wonder if the same method is recommended to roto walking humans/animals?

I have a footage of a person walking (side view), so I tracked the person’s head and then tried to link my roto shapes to the track. But the roto shapes of the limbs do not follow the track very well. And I noticed that it’s difficult to track walking persons head (as I understand, if I want to link my roto shapes to a track, the track itself must be almost perfect).

So, should I use the method described above to roto objects like this? Maybe I should re-shoot the video with a person walking in the background with more contrast?

Here is the footage which I’m working with: - YouTube

Note that I do not intend to rotoscope entire 3 seconds - I only need 13 frames (during which the walking person completes 2 steps)


Thank you

So yes, you should use this method if you are a beginner at mocha roto for all things, people, objects, animals, etc. As you get more advanced though, you can track and roto at the same time. Not that if your shapes are drifting, your track isn’t very solid. Turn your surface tool on to see what the track is doing. I also recommend NOT using perspective with roto, use only translation, scale, rotation, and shear for rotoscoping. You will end up with better shape data to work with most of the time. There are, however, exceptions to every rule. The more you use mocha the more you will intuitively know what those exceptions are.