Rotobrush Brushbeast

[Sanna Pospicil]

HelloI want to use roto brush tool, but it doesn't work. When I choose roto brush tool and start selecting what I want, the whole video border turns purple, meaning the whole image is selected. I don't know what I need to do, to just select what I want.

So I took a screenshot of your screenshot and as I suspected there are very few contrast and color differences in your footage for Rotobrush to work with. I didn't get the entire frame but when I tried to mask out the left leg there was so much of the image selected using the default Rotobrush settings that I could tell that Rotobrush would have a very hard time finding edges. The solution is to do some color correcting before you try and use Rotobrush. My first choice was to add Black and White

Without knowing what your footage looks like, nobody can tell you much. Presumably the footage simply doesn't have enough contrast to allow the tool to detect any edges, but who's to say? You'd have to provide at least a screenshot.

Mylenium: Here is screeonshot. I tried on another video where I know edges are better, but it still didn't work. I tried some things, and I click on the icon I marked with red (set IN point...), and then this one frame where I click it, it choose what I want. But then another frame not anymore. I know this isn't right way to do it, but I guess it shows there are enough edges. So I really don't know what to do.

So I took a screenshot of your screenshot and as I suspected there are very few contrast and color differences in your footage for Rotobrush to work with. I didn't get the entire frame but when I tried to mask out the left leg there was so much of the image selected using the default Rotobrush settings that I could tell that Rotobrush would have a very hard time finding edges. The solution is to do some color correcting before you try and use Rotobrush. My first choice was to add Black and White and really jack the values around. It became much easier to cut out the left leg. When you have the roto completed, propagated and frozen, then you can turn off the color correction or just delete it. I hope this helps.

I'm having that issue, but can't adjust the framerate of the composition. I work with a lot of stop-motion footage of varying framerates, but edit my compositions in 25fps. Pre-composing the footage before trying to roto it doesn't help.

Hey this just happened to me, same purple box around all of the footage in the layer edit panel. I also have footage with a limited amt of contrast, but I find that the RotoBrush (2.0) will still do a pretty good job of pulling something out of the footage, not simply producing a big purple square around the whole frame of the footage.

I realized my footage and composition framerates were off. Footage was 23.976, comp was at 30. I got an error in the bottom of the layer edit panel that said as much. After changing the composition fps to 23.976 in composition settings, I tried the RotoBrush again. The error went away, but still the full purple square.

I deleted my footage from the timeline and re-imported it into the comp from the project panel with the matching fps (footage, 23.976 / Comp @ 23.976), and voila! The RotoBrush performed as expected. Now to adjust that contrast...

Just my 2 cents!

Just a heads up to anyone who does a TIME STRETCH to their clip, AE will ask you to change the comp to the new frame rate. This however doesn't mean it rotobrush will now work. You must revert it back to original time (100 in time stretch settings). Do the rotobrushing and then auto trace....and finally you can times stretch.

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