What do you call a "hidden" shape denoted by a dashed line?

Solution 1:

If I understand you correctly: When one object occludes another, you want to the occluding object to become transparent to reveal the occluded object. Like this:

I’m going to go with see-through view, taking cues from this loosely-related whitepaper: Visualization Methods for Outdoor See-Through Vision

I’ll let you muck around in there for more ideas, but here’s the opening sentence:

Visualizing occluded objects is a useful applications of Mixed Reality (MR), which we call “see-through vision.” For this application, it is important to display occluded objects in such a manner that they can be recognized intuitively by the user.

X-ray view might work too. If you need to refer to the actual dotted line, perhaps: wireframe.