I'm trying make virtual objects be hidden when a real world object is positioned in front of it, but not having any luck with it, i've been playing with the occlusion settings in unity but the virtual objects do not become hidden?
You could fix this problem by building your augmented reality scene with the experimental meshing enabled.
Here is an example of the concept https://www.youtube.com/watch?v=sn3bhnPlfcw
You then could ray cast from camera to the virtual object and turn off the object if a mesh blocks the raycast.
+1 on AndrewNakas's solution.
Another solution is to do the screen space depth buffer test. That means taking a depth image from the point cloud Tango provides, and compare it with the virtual camera's depth buffer.
Tango Unity SDK implemented this feature on the Tango AR Camera prefab. There's a checkbox named Enable Occlusion.
来源：https://stackoverflow.com/questions/34957433/occlusion-in-ar