Your thread made me think of this script a friend made. Junk Pile Maker. http://filipericsson.com/ You select meshes you want to use and the script makes a junk pile for you. So If you want to do that you should start off by creating some junk assets and I'd probably say that you should use 1 material per asset. So fill…
I'd say separate UV maps if you want to mix the assets for other usage. The type of objects you are mentioning though is maybe not very relevant to use with that script.. A pile of dirt is more of sculpt kind of think i suppose.
So I could just make 4 different objects and use that script to throw them into a pile. Then I will have to make separate materials/textures for the 4 parts and somehow fit them all into one UV map with no overlapping UVs (UE4 does not like overlapping UVs). Does anybody know how the debris was done in Gears of War, Metro…