Best approach to track an alpha clip

Hi, i have a mp4 alpha video clip, basically all black background with a person all white in the foreground (see screenshot). I thought this would be super simple since it’s black and white but I used the magnet tool which worked very well and then started the track and it didn’t follow the layer well at all. I’m guessing I’m doing something wrong to get such back results but if anyone can help me please I would appreciate it.


Hi. Is there any specific reason why do you need to track the alpha in the first place? Mocha is designed to track texture patterns, and not the one-colored silhouettes.
Magnet tool would actually work great on such contrast contours for drawing the shape. But speaking of the tracking - having no texture would most likely lead to fail. Do you have an original movie file to track?

Ok, so I used the actual vid which has a transparent background and changed the canvas color to something more neutral thinking it may help. When using the magnet tool the path seems to zigzag in an out instead of staying on the outside of the person since it has a perfect contrast between the person and the background so I click which seems to be too many times around the person thinking I can use the snapping tool but the results are even worse. I understand what its trying to do but in my case it’s being way too smart about the selection. Is there a way to “dumb it down” and simply select the outline of the person almost like using the “quick select” or “object select” tools in photoshop?

For the Magnetic tool you can reduce the Detail parameter to reduce the number of spline points
Have you checked the Area Brush tool? It works similar to Photoshop quick select


Thanks, tried both and basically end up with the same results. Sorry for the back and forth but I would have assumed that having a alpha and/or invisible background would make this so simple considering most apps have a lasso type feature that basically selects the outside of a shape when there is an invisible background or actually a solid color background that doesn’t match the outside pixels of the shape. I would recommend, if not already in the pipeline, in the next update. It’s already difficult to have to use so many tools these days, keeping up with learning updates etc… This feels like a lot of work for what seems like a simple task for most apps/tools.

I personally use regular X-splines like 95% of a time.
What is your end goal for the shot? In case you already have an Alpha, I’m assuming that you’re not trying to do the roto but something else.
For tracking purposes garbage mask can do the job, not requiering a lot of the time for drawing.