Problem rotobrush

[MatheusRochaaa]

I have the problem as it appears in the video: when I select the object with the rotobrush and press 1x PgDn, the selection exits the selected object. what do i do to solve this problem? I've tried with other videos, but the result is always the same...

[Mylenium]

There's nothing to see here. You need to provide an actual link to your video or embed it here (as long as it fits the 40 MB limit) plus of course even with the video you need to provide exact info on your system, effect settings and whatever else may be relevant.

Mylenium

[Mylenium]

Okay, your video suddenly appeared (probably a forum glitch) and now everything is clear. Rotobrush does not work on images that have no "real" motion. Your strawberries are merely rotating and there is nothing Rotobrush could latch on. You need to use masks or simply key out the green background, which likely is the intended procedure, anyway.

Mylenium

[MatheusRochaaa]

But, every video I make happens the same thing. I recorded a video making a move and the same thing happens.

[Rick Gerard]

I am not sure why you are using Rotobrush on Green Screen footage. The boundary overlay is pink, so you are not looking at the matte overlay. I see a bit of expanding going on, but this is probably normal.

Rotobrush is a tool of last resort when you have to separate an object from the background. It does a pretty good job if the object you are trying to isolate has good edge detail, minimal motion blur, and different color and luminance values than the background. Using Rotobrush on Greenscreen footage is about as efficient as hammering nails with a screwdriver. 

Ctrl/Cmnd + Left or Right Arrow might be a better way to move the CTI one frame to the left or right. 

[MatheusRochaaa]

I understood. However, I still believe that the problem is something specific, because a friend managed to do rotobrush perfectly with this video.

[MatheusRochaaa]

Here's another video that has the same problem. What will be the cause of this problem?

[Rick Gerard]

What is the source of the footage? I'm guessing it is an MP4 and possibly has a variable frame rate. 

Is the Composition Panel set to full resolution?

I always trim any footage that needs the Rotobrush tool, add garbage mattes and color correction if needed, and then Pre-compose, moving all attributes to the new comp. I then run Rotobrush on the nested comp (the pre-comp I just made. That can solve frame rate problems and, occasionally, MP4 decoding issues. 

You probably also should check your GPU drivers and the Project Settings.

That shot is another example that I would not try to rotobrush. Because it is a simple shape, it would be a lot easier just to draw a mask and then animate it with a few keyframes if needed. If the thin black lines are artifacts, you could even use Keylight, then invert the Key to isolate the yellow triangle. 

[MatheusRochaaa]

The video is MP4 and the settings are in the standard used normally. It's in high resolution.
I know there are simpler ways to do this effect, but what I'm having problems with is Rotobrush and I used a simple video to show that this tool is not working on my computer. I installed After effects on my sister's notebook and I was able to perfectly do the rotobrush in the strawberry video.

[Rick Gerard]

You have a GPU problem. Try a different After Effects version, update your drivers, and reset your preferences. That is about all I have got. 

[MatheusRochaaa]

I installed version 22.2 but this message appears. How to proceed?