Tracking Slipping + Removal Issue

Hey there,

I’m looking to get some help with my track. I have a bag spinning on a turntable. I’m tracking the front and the back to replace with a logo.

The front of the bag tracks smoothly until the end of the clip where it starts to slip. Additionally I created a clean plate to remove the tracking markers but it is not rendering. Instead I the error mesage, unable to replace layer pixels: no active layers found behind the layer.

So this is a three part question.

  1. How do I keep the planar surface from slipping from the front of the bag at the end of the clip.

  2. How do I keep the planar surface from the back of the bag from slipping.

  3. How do I get my clean plates to render when I import cleanplate?

Link to video below.



  1. That’s quite a tricky track as you don’t have a lot of texture detail in the bag but try extending the background track shape out past the edges of the bag to give the plane some definition.
  • You could also try upping the contrast of the image to see if any more texture detail pops out, either by changing the colorspace settings in standalone, or in the plugin, adding a contrast effect and precomping the effect before tracking.
  • Also, don’t cut out the tracking markers in your track as you’re losing useful information. It looks like you’ve added a contour to the same layer, which is going to cut a hole in your track shape
  1. If you can’t see the back of the bag, Mocha cannot track it. There is literally nothing to track. You will need to stop the track before you get to the point where the back disappears and end the layer by adding an out point to the layer range in Layer Properties.
  2. If you are performing a remove, you can use a clean plate clip, but you need to have two layers: The forground and the background.
  • Remove always requires at LEAST 1 foreground and one background layer to remove.
  • The back of the bag is no the right layer for this, as it doesn’t contribute to the remove you’re trying to do.
  • To do a clean plate remove for the bag, duplicate the tracked layer for the area you want to remove and add the clean plate to that layer.

Hey Martin,

Thanks for you help! I’m working on the remove now and will adjust my shots to exlude the back of the bag.