Tracked Shape as holdout for newly tracked shape

I was working on a job when I discovered this wasn’t working quite as I understand it should. So I meticulously followed along on Ben Brownlee’s tutorial for proper steps to do this and I do not think it is working as explained in the tutorial 01A Planar Tracking Improvements or in the manual. If track the shape that I want to use as a holdout matte to prevent floor (“Ground plane”) tracking from using the door features, then make the door shape a subtractive blend mode over my floor shape and layer, then try to select any combination of the floor and door, the tracker always adds features to the combination of shapes selected (as if adding to each other). It does this when selecting layers or shapes, floor selected before door, etc - all don’t matter. If I hand animate the door shape on top of the floor outside of a layer, and set that as subtract it clearly shows planar tracking points disappearing from the subtracted shape. Is this the way it is supposed to work? I can send screenshots if not.

I posted about the same issue 2 days ago. Tracking goes wacky
No response to this issue. Apparently there’s more important matter such as messaging users and ask for their serial numbers when they’re 3 days in a 15 day trial.
I assume you used the Silhouette’s planar tracker and the features you’re talking about is a point cloud.
I used the mocha tracker in Silhouette and I even posted 2 screenshots than the mocha plugin does work properly unlike the mocha tracker in Silhouette when it comes to subtractive shapes

One thing to do for wacky tracking is to make the features stand out more with the pre pressing by increasing contrast, gamma, and denoising. By checking the “preview” in that area you can see how you are making the features stand out more. I am specifically referring to making sure a moving occlusion doesn’t interfere with a track by tracking a roto shape that blocks the tracker from seeing the features of said occlusion.

I’m confused. I thought you were talking about the occluded shape not being subtracted when tracked and instead following the main shape.

Welcome @jason6

Please do the following:

  1. Place the occlusion shape and layer at the top of the stack.
  2. Set the top layer’s (not shape) blend mode to Subtract
  3. Ctrl/Cmd-select the main layer you want to track first and the occlusion layer second.
  4. The planar tracker will now show track points outside of the occlusion

Perfect. Thanks Marco. This worked exactly the way it should. Maybe an email to curiousturtle is proper channel of notification, but I would perhaps suggest inserting a re-edit into Ben Brownlee’s Mastering Si V7, 01A Tracker improvements to follow this guideline. In his tutorial he clearly selects the holdout shape changes its mode and does not use the holdout layer - which does not work. I just A/B tested this. (Unless you are planing on making it also work that way in the near future).

Oh, Your thread had many complaints about the tracker and form my brief perusal it seemed your issues where more tangential to the subtraction shape. That is, you were attempting to track non co-planar areas which make shapes do all sorts of weird things. And you were also trying to track areas that had little to no detail, which could be enhanced to help the tracker by using the Pre-Processing area of the tracker.

@jason6 I don’t have quick access to the video you are referring to, but you can use a shape set to subtract as a holdout above your tracking layer as long as the shape is not in a layer. Once the shape is in a layer, the final layer alpha controls the holdout. If there is only 1 shape in a layer and the shape is set to subtract, the layer won’t have any resulting alpha.

Cool. Thanks Marco! That a good way to wrap my mind around why it didn’t work and is indeed confirmed when showing the alpha in the viewer and playing with blend modes of each element. The video I am referring to is part of the paid tutorial series I downloaded directly from Boris, although I know Ben Brownlee has been part of Si from before Boris bought Si and makes these tutorials at least partially independently. The user guide also only explicitly outlines a different way of doing this that would only account for objects that are tracked going the same direction (Shapes only, and shapes inside the same layer being tracker)

@jason6 I’ll add to the tracker tutorial to cover the shape in a layer occlusion case.

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