How to cut a human figure from colorful background and why ROTO not working

[afjka]

Dear all,
I'm an editing beginner and new to PR and AE.
I have a 4 seconds cartoon video and I want to extract the human figure in it, (i.e. cut the background) so that I can put it into a different background.

After searching online, I found that ROTO from AE might be the best option. However, it does not work at all.
What I expect, and just as in tutorials online, I use ROTO to draw a green line across the figure's head, there should be a purple circle around the head, and I can adjust later to be more accurate.

What happened to me was that, no matter how I draw the line, the purple circle it generates simply covers the whole screen, as shown in the following picture,

[Attachment 56045 - Click to enlarge]
You can see the purple rectangle around the screen if look closely.

I have no idea why it is so. Could anybody help?

Besides, I also tried some other ways, like, import the video to PS and do the work there. Since my <4 seconds video only have 30 layers to edit, it can be done but still too exhausting. And I'm also new to PS, not very sure how to deal with those pics.

If there are other ways to help me cut the human figure I want to put in another background, please do let me know. Thanks a lot!

[Cornucopia]

Haven't used ROTO in a long time (decade?), but making an educated guess:

Roto should operate like a smart lasso. Iow, you shouldn't just draw a line - you must loop one end of your line back to the other end so that lasso knows which region to include vs exclude. Without that, it would include (or exclude) whole screen region.

The MANUAL should be your friend here. Or YT videos even.

Also, depending on the lasso's expectations, you might need to already have duplicated the video layer and be using the upper layer. Like in Ps it might have issues working on a background layer.


Scott

[poisondeathray]

He's referring to rotobrush


It could be your brush size is too large - hold down ctrl+left mouse button, drag left with mouse to decrease the size, then try again

Try a (-) stroke , by holding alt key , hold left mouse button while drawing somewhere around the background (exclusion area that you don't want)

Also try rebooting computer, restart AE. Maybe some weird bug

[afjka]

Thanks Scott and poisondeathray, for your warm replies.
I've tried everything u mentioned.
open in an upper layer, draw a line back to the other (or many other ways of drawing), reboot computer/AE, change the brush size
none works.

Thanks anyway. Could the reason be that, the figure I tried to cut does not move a lot? (I'm thinking ROTO as a tool to capture moves
I export the video to PNG sequence and then edit in PS and then back, 30 pics, 2 hours. Solved my problem for this time, but I'm afraid I'll HAVE TO use ROTO in the near futrue.

[smrpix]

Maybe try uninstalling and reloading AE. FWIW I had no problems with rotobrush using your image. My selector was smaller than necessary if that's any help.