Does this workflow make sense, any tips?


So I have a 1 minute (1400+ frame) sequence shot from a tripod that shows two talents having a conversation. The frame never moves, and there are some scene cuts every 15-20 seconds or so, which in retrospect would have been good stopping points to just use fresh roto shapes, even if it meant spending time recreating the start frames at every cut, but I figured, lemme just use the same shapes the entire time. But there was so much head turning in some spots, that I ended up added a bunch of extra points for those sections, and after finishing all the roto, I see now on playback that the edge movement is so jittery with all those points, and seems very noticeable, especially because the people are standing in front of a window with a lot of glare and other colored reflections coming through, so you can see various edge colors popping in and out.

I thought all my roto work was wasted at this point, because offsetting the shapes outward and feathering them just didn’t blend well with my night time cityscape replacement background, even though it removed the jitter from the face edges of the talent.

Having no idea what else to do to salvage this, I tried actually using the ‘matte repair’ node and just shrunk and feathered the shapes enough so that the only thing you saw as was a fairly stable/non-jittery roto (although extremely shunkn and feather). I then used 3 different zMatte nodes, one set to ‘luminous’ for isolating the hair, one set to ‘luminous’ for isolating the skin tone, and one set to ‘hue’ for also isolating the skin tone. I used my shrunken Roto as my ‘Hold Matte’ input and actually also connected the original jittery roto to make another ‘matte repair’ version of the Roto that was expanded and inverted, and I used this as my ‘Garbage Matte’ input. I did this for all three Zmattes (6 zMattes total because I did it for each talent). I then used a few ‘composite’ nodes, to combine all the zMattes and the end result actually looks good to me now, no more edge jitters.

I quickly glanced through the 1400 frames just to see if it holds up, and it looks pretty good, although I did see some spots where I will need to either go ahead and break up the sequence at those scene cut points, so that I can make some slight tweaks on the zMattes for each section, or just maybe add in key frames for the start and end of each section in the zMatte values.

The one thing that seems a little tricky without doing more clean Roto is that there’s some hotspots that blend into the edges of the talents skin. Any thoughts on how to further knockout the hotspots from the talent edges or some other technique to try?

Overall, would anyone have any other broad stroke tips I could use for further refinement or isolation of the talent given where I’m at now on this project?

This was the first time I’ve tried multiple zMattes, but is using multiple zMattes common for difficult isolations? Is it common to just use a shrunken feathered roto as a ‘Hold Matte’? Just wondering.

Any other tips for starting future projects similar to this would be much appreciated!!! Thank you!!!:slightly_smiling_face:

@persyst Check out the Roto Tips sections here:

A number of the tips apply to your situation.