Trouble with intersections and normal maps.

Udjani

For the first image, lets say i want to bake that detail into my lp, and i want it to have a bump in the lowpoly but without having to merge the vertex of the bump, just having it floating there, how to do that? i tried some stuff, but all of them end up with horrible results. 

For this second one, i was searching on sketchfap and artstation to have an idea of what to do, and in this situation seems that people just intersect those pieces which end up with a very sharp intersection. And i was wondering if there was another way of to do that.
 

I tried two different approach, but they both seems to be kinda meh, one, i baked the 2 pieces separately, to intersect them after, and the other i just baked them together. Also, if the normal map don`t catch those intersection, how will you paint rust and shit there?

Neox

how close will you really get ingame? that is the only thing that counts. ignore the moments when someone searches the level for normalmap errors with a sniperrifle

if you really get close enough without doing any stunts so this becomes obvious, i would argue spending the right amount of polygons and meshing it together is a totally valid approach.

EarthQuake

Just merge into into the mesh. The few vertices you save are completely irrelevant with modern hardware. Plus, merging it means better UV usage.

Unless it should be a separate object for some sort of logical reason, like it's a part that will animate, can be removed, or will make it easier to bake without intersection errors, you should make the lowpoly a watertight shell.

Here's an example, you can turn the wireframe on in the Viewer scene: https://www.artstation.com/artwork/EmOeK