How to animate the disappearance of a mesh I have this strip on my landscape that I want to make disappear from where the digger currently is, and then following the digger towards the end of the strip, to reveal the trench underneath.

What is a good way to do this? Can I animate an object that removes the ground strip? The camera is static in this scene so I could also imagine using a mask, or doing something in the video sequence editor.

*Cutting out my strip (knife project) messes up the connection with the rest of the landscape (they both have displacement maps). So I think I need to keep both images and animate a mask in the video sequence editor or something.
To get the cleanest result I suggest animated booleans. Since you have flat shading you wont get any shading artifacts, this is probably the textbook example for them. If you have some subsurf and displacement apply them or put the booleans after the displacement.

There will be 2 boolean objects.
- First one is static and will create the hole in the ground (highlighted). Put some edgeloops in the ground object around the trench so this boolean wont segment the whole thing.
- Second one can be just an animated cube and will intersect with first boolean object and the concrete wall inside trench. The bigger the intersection the more ground will be removed and more concrete wall will be shown.