Low-Poly Normal Question

tyl3r

I was wondering if I could get some help with some hi-poly to lo-poly baking questions.

I recently finished up a high-poly model and was creating the low-poly for it to bake from. This is the first time that I have done something a little more advanced for me and had a few questions!

So this is just a small piece from the model but I can apply the results to the other parts of the model.

So here is a picture to help illustrate my problem:


I am wanting to be able to bake the normals from the high to the low here but I don't know how low I am able to make the mesh because I still want to be able to have it look close to the high. So Lo1 is a basic low mesh and Lo2 is pretty much the same thing with a slight bevel. So...

1. Is a small bevel like that (Lo2) needed to achieve that edge spec/roundness from the hi-poly?

2. What's the best way to setup the UV's for the low poly mesh to get the proper bake?

3. Which edges do I soften and which do I need to harden (Maya user) to get the proper bake?

I have tried out a few ways already but none were really satisfactory so I decided to come here for a little help.

gsokol

1 - In this case beveling the edge won't make too big of a deal. There isn't too much going on in the corner of your highpoly there, so I'd stick with Lo1.

2 - You can unwrap however you normally do, but don't overlap UV's. Even if you plan on doing it in the long run, make sure there are no overlapping UV's during the bake, and overlap them when you are done.

3 - I would handle edges the same way you would if this wasn't getting normal mapped.

tyl3r

Thanks for the reply! I finally achieved something satisfactory! I made a stupid mistake and was trying to bake while my hi-poly was on 3 in Maya instead of actually smoothing it manually. Once I did that the bake went much more smoothly.

The only question I have now is when baking, for a better map is it necessary for your lo-poly to be just inside of the hi-poly?

DennisGlowacki

I agree low1 is better. But you may want to soften the edges. It may look a bit wierd but once you do the bake and see it with the normal map I think it will return better results then having that hard edge there. I would be interested in what other people think of that.

You may also want to try Xnormal for baking. I'm also a maya user and I've done tests like this too but once you do something more complex then a single object you may find that you are back to Unsatisfactory results.

Good luck.
Do you have a thread with the full model?

frazzled

I'm also a Maya user and really struggle with this on non-organic, hard surfaced objects when trying to make them into game assets for the UDK. If you soften the edge, the edge will turn out pretty well but the flat areas will reflect light in a "distorted", blobby way. If you harden the edges, the edges become seams, but the flat areas now correctly reflect light. Damned if you do, damned if you don't, I've read a ton of normal map tutorials and never gotten a satisfactory answer. Does everyone just go "yah, it has seams, that's life" or "yes it lights oddly, that's life"? It's hard for me to believe, so I assume I'm doing something wrong

There was another great thread here on normal maps and hard edges, I read it as well, but everyone had a different opinion and no one really offered up a complete solution Pretend he wanted to get his above asset or a simple cube into a game with a normal map reflecting the nice beveled edges of the high poly onto the low poly. As he asked, 1) should his low poly have beveled edges or is he ok with the 90degree angles, 2) given that UV's define seams in normal maps and generally people don't want to see seams, what would be the best way to split up his object or a cube, 3) specifically, what edges should be softened, all of them, just the "hard" edges, none of them, etc?

I've found a ton of threads here and elsewhere where people struggle with this and not many satisfactory answers The more specific the better!

Frazzled

tyl3r

-DennisGlowacki: After my quick tests, I found that softening all edges except the one where I separated the UV's, (the cap) gave the best looking results. The entire thing soft had a weird shading issue.

I tried xNormal but it wasn't working for some reason... the map was coming out a weird green color almost like an object space map but it was set for tangent space... I might need to reinstall the program to return everything to its defaults though.

As for a thread... not yet, I plan on posting one up soon, I'm just finishing blocking out the low-poly (it's not a complicated prop) but i'm taking my time and trying to do it right but i'm sure i'll run into more problems and will have more questions sooner rather than later!

HAL

The entire thing soft wont really workas the shading would be interpolated over the whole (pretty low) geometry hence the weird look. You would have to use smoothing groups OR bevels for that purpose to keep thesmoothing nice.
Be sure to split the uvs when sticking with the first mentioned method.

I recommend a read of this thread here:
Too much optimization

I also suggest a read to the ultimate al end to normalmaping thread here:

http://boards.polycount.net/showthread.php?t=48305

e:// also for xnormal make sure that the two meshes are at the exactsame position otherwise you could get that weird stuff out of it.