Virtual Texturing Feedback

Hi, beningram.
My question is about Virtual Heightfield!
I just found out that Unreal 4.26 has such a feature and I prepared this tutorial for it:

but there are many things that there is no explanation for it.
Is it possible to use a texture instead of mesh to create a decal-like heightfield? and is it possible to create a negative height?
and can you explain a little more about Virtual Heightfield?