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Eddie GaliRotobrush Issues
by on Mar 21, 2013 at 5:53:17 pm

I have read everything that Adobe has to say about the Rotobrush, watched multiple tutorials, and read articles. They all say how to use it, but no one mentions things like when you do a brush stroke over something you want the Rotobrush to include and it just says, "No... no we're not going to add that, no matter how many foreground strokes you draw over it."

It still doesn't seem to work the way I want it too. Are people using this as effectively as regular rotoscoping?


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Dave LaRondeRe: Rotobrush Issues
by on Mar 21, 2013 at 5:58:28 pm

...and is Eddie Gali using Rotobrush with the layer opened in the layer window and not the comp window?

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Greg NeumayerRe: Rotobrush Issues
by on Mar 21, 2013 at 6:23:25 pm

I love it. But, yeah, it took me a few minutes to figure out that I needed to be in the layer window, as Dave mentioned.

When I notice it being stubborn - i.e. it can't seem to identify the edge I'm highlighting -- I make sure I put both green strokes and red strokes in there. I'll go back a forth a few times, but eventually, it cleans up, even if it doesn't understand what I'm differentiating. I think the key is to make sure you don't cancel out your "include" strokes with your "exclude" strokes.

For example, I needed to extract a moving, blurry hand. First, I quickly "green stroke" the basic hand to see how it does. Then I switch and "red stroke" the places that it thought were hand but weren't. Then, as I get into those blurry fingers that it's still confused by, I keep going back and forth, green, then red, to define my "include", and then my "exclude" lines. The more you do it, the more it builds up a map of what you want. Where it lacks your input, it guesses, but where you have many strokes, it follows them. It's a bit weird because it's like painting with invisible yes/no paint. It's taking my strokes, then guessing at the parts between them. So if I paint a green right up next to a red, it "should" put it's edge right between them, because I've taken all of the guess-work out of that spot.

Then, I advance a few frames to an obviously wrong frame, and do it again. Roto will take your input for those frames and try to interpret the inbetweens as well, so don't go frame-by-frame at first. Let it try to figure it out with a few key frames you have. So I'll do frame 6, then frame 12, then 18, then go back and do frame 9, then frame 15, and keep focusing down until I've got it the way I want.

Antifreeze Design
http://www.antifreezedesign.com


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Eddie GaliRe: Rotobrush Issues
by on Mar 22, 2013 at 4:39:28 am

Thanks, Greg! Do you find the brush size makes a big difference as well?


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Greg NeumayerRe: Rotobrush Issues
by on Mar 22, 2013 at 5:26:50 am

I would imagine that brush size helps AE identify the edge that much better, but I don't think about it as much because I'm using it on a Wacom that adjusts my strokes to my pressure. The pressure sensitive pen is handy because I can throw down some fat strokes around the inside of a hand shape, then as soon as AE "solves" that stroke, throw in a few light thin strokes around fingers that goofed. Then, I'll (hold Option, I think) throw a few red strokes outside the hand where AE mistakenly had background footage in there. I just keep going back and forth until I like the frame.

While it's beneficial to skip a few frames ahead and let AE try to interpolate, I haven't found any benefit to creating an unfinished roto-matte on any particular frame, since AE is using the frames you manipulate as it's key frames. Make the frame you're working on great, so that AE has as much to work with as the robot works forward and backward from that key frame as far as it can.

I usually try to start with a frame that's generally in the mid-portion of the time duration, and one that's not too unique. For example, for a recent hand shot, I used a place where the hand was relatively still. Then, as the hand moved a few frames later, AE already had a vague sense of where it was, but it needed lots of assistance on the fingers where motion blur made them semi-transparent.

Antifreeze Design
http://www.antifreezedesign.com


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Eddie GaliRe: Rotobrush Issues
by on Mar 22, 2013 at 3:10:43 pm

I guess what isn't working for me is the back and forth between foreground and background strokes. I have started from scratch a few times and tried different combinations of large and small brushes and variations in the distance between foreground and background strokes, but literally nothing is changing at all. I have tried to be very precise, but once it gets to a certain point the matte doesn't change at all, no matter how many other strokes I may continue to lay down.

And it's literally the same thing you are talking about. Hands with motion blur. It's masking them so her fingers disappear almost completely. She looks like she has tiny little deformed hands and I can't seem to coax the rotobrush to expand the matte even in the slightest bit.

Any other advice?


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Greg NeumayerRe: Rotobrush Issues
by on Mar 22, 2013 at 4:35:19 pm

Hmmm. That's a tough one, since even screenshots don't really help explain your issue, or show the process. All I can say is remember that AE is ultimately only going to have a couple options for any given area. It's either: Foreground or it's Background, and then your other adjustments in the Roto effect panel will help you soften that transition between the two. (that's my understanding/experience of the process. Anyone should feel free to clarify/correct me) So, I think you'll have to say, "Ok, it's a blurry edge, but the mid-point is about *Here*." Then, put your strokes right next to each other (no gap) so that AE can also picked that mid-point. Then, adjust your softness/feather in the Effect panel to blend that transition.

Remember that you're not creating the blend with the red/green. Don't mistakenly think that the distance between your strokes creates a blend. Any distance you create simply creates a larger area for AE to try to solve where the dividing line is. But if I understand correctly, it's a hard---albeit possibly quite complicated---mask line. The softness happens in the adjustments.

Antifreeze Design
http://www.antifreezedesign.com


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Eddie GaliRe: Rotobrush Issues
by on Apr 5, 2013 at 7:45:22 pm

Greg! My savior!

I am quite ecstatic to inform you that after not giving up on your initial explanations I continued to attempt explaining to the Rotobrush exactly what I wanted from it.

What ended up working the best was simply this... I adjusted the size of the brush to that of a pixel. I would zoom in and literally draw on the pixels that I didn't want to include in the matte and suddenly (sometimes after a single stroke, sometimes after multiple strokes) it started to see exactly where I was telling it not to go.

I just want to thank you for improving my work flow and giving me a new technique that I will surely use for years to come!

Best,
Eddie


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Greg NeumayerRe: Rotobrush Issues
by on Apr 5, 2013 at 7:49:08 pm

My pleasure!
Glad it helped.

Antifreeze Design
http://www.antifreezedesign.com


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Eddie GaliRe: Rotobrush Issues
by on Mar 22, 2013 at 4:36:42 am

Yes he is!


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