Generating Normal Maps using xNormal

[Kyle_Katarn]

I've been hearing a lot of good things about xNormal, and I have a few questions about the UV Map itself.


Do the UV Maps for both the high-poly and low poly mesh have to be relatively in the same place?
Do I need to follow some special template for unwrapping similar to that of Character Models?


Thanks for reading, and hope to hear a reply soon.

[geodav]

don't bother uv mapping the high poly unless you want to not required afaik
no need for special templates either but i'm not sure how xnormal works with overlapped uv's

[tyrone70]

it doesn't work well with overlapped uvs. artifacts pop up like crazy. polycount.com has a VERY bug thread on the program in its technical talk section. I would go there if I were you.

But in my honest opinion, xNormal is the best program for that job. it's only weakness to me is the cage building (if you need one) but that's about it.

[danimal']

I've been hearing a lot of good things about xNormal, and I have a few questions about the UV Map itself.


Do the UV Maps for both the high-poly and low poly mesh have to be relatively in the same place?
Do I need to follow some special template for unwrapping similar to that of Character Models?


Thanks for reading, and hope to hear a reply soon.

1. No, your high poly doesn't even need a real UV map at all. Only the low poly UV map matters. To over simplify the process, what xNormal will do is put the high and low poly meshes on top of each other and compare them, it then writes the results to your low poly UV map; so only the low poly UV map matters. This means you can create a low poly, not UV it, jump immediately into a high poly sculpt, finish it, THEN UV your low poly after the fact and it's all good.

2. No special template, but game UVs have different issues than "general 3d" UVs (people who do non-realtime can get away with a lot of practices that won't work in game). In particular UV edges can create seams in UE. So, when working with the UE, avoiding seams unless really necessary, even at the expense of some distortion is what I'd personally recommend (others may disagree). But the general rules for UV mapping in games is like anything else: create your seams in places that either make sense to have a seam, or hide them in a place the player is unlikely to see often (like under the arm in a character).

Definitely use xNormal, its brilliant not just for normal maps, but AO maps, transferring poly/vertex painting, etc. Ridiculously fast. Depending on what your 3d program is, you may have to invert the green channel on your normal maps (if so, in xNormal there's a ... next to the normal map, click it, and flip Y+ to Y-).