terrain reticle/see though terrian

Hi there

I am a bit new to the Unity development arena and was looking for some advice/help to make the below, If you take a look at this video of 'Homeworld: Deserts of Kharak' ["utube vid link"][1] at around the 3:11 mark you will see the effect that I am trying to replicate including the height information.

We are building a 3D environment using real satellite data imagery and height data. I then want to be able to do an X-ray type vision through the procedural generated terrain to show detailed geological information underneath rock formation, ground water etc..

Now I have a couple of ideas for this and was wondering if any one has done this type of thing before and can offer hints, tips, full code :) that sort of thing.

Idea one: procedurally generated terrain on top then a second procedurally generated terrain with geological information just below the first. Then build a x-ray culling shader to highlight an area underneath making the top layer see through.

Idea two have separate terrains but two cameras one on each and then mask the second camera over the first to show the highlighted area.

I am open to ideas and best solutions asset store recommendations etc. please help thanks [1]: https://youtu.be/p_prxFpXESA?t=3m08s