Perception Package, Segmenting Specific Surfaces

Using the perception package I understand how to do basic object segmentation, but I was interested in automating more advanced forms types of annotation such as specifically segmenting out the top surface of boxes. For example, imagine a pile of boxes with a camera looking down on them. For this, I specifically want to segment out just the top surfaces of the boxes, not the sides. Would it be possible to create a new segmentation type for this?

Another option for achieving this that I have thought about is creating a box made of 6 objects, so that each side is labeled separately. However, for this to work, I would need to be able to turn off the sides that aren't facing upward. I haven't found a way to turn labels on and off while the sim is running. Is this possible?

Thanks!

 

Are the boxes dynamic in the scene, as in, are they going to be able to rotate? Because if not, if you know that one side of the box is always facing up, you can create a box that is made of a couple of meshes and only label the top mesh. In this example below, which is very trivial and I wouldn't recommend doing it like this because of z-fighting issues with the top plane and the cube, I have only labeled the 'Top' plane game object with a "BoxTop" label. The final screen shot shows the results of the semantic segmentation labeler. Like (the other) Steven said previously, if you have a dynamic scene then I think you will have to turn on and off the labels on the sides based on the dot product between their surface normal and the Vector3.up normal.

 

Yes, the boxes will have a random orientation. I tried out Steven's method of turning the labels off and on using getComponent and it works great! Thanks!