Maya transfer maps help

matr1X

Hey all, im just testing the transfer maps feature on a simple elongated cube. When baked im getting some strange errors in the normal map and im unsure why. I have laid out the uv's for the low poly and sewn the edges accordingly but the normal map picks each sewn edge if you like and puts a crease down it.

If anyone could help me it would be much appreciated!

Thanks, Adam

haiddasalami

Are your edges beveled so they are not 90 degrees?

tyl3r

Can we see some screenshots perhaps? It might help us figure out what is going wrong.

Firebert

read through this article and it should clear up your problem

http://www.svartberg.com/tutorials/article_normalmaps/normalmaps.html

PredatorGSR

In the advanced settings of the transfer maps wizard, set it to geometry normals instead of surface normals. Surface normals will give you a seam every time but better interior details, while geometry normals will give you smooth edges but some details might be distorted.

If that doesn't fix the problem, please post your low poly mesh so we can see the normal shading, your uv layout, and what your normal map texture looks like and we can diagnose it.

matr1X

http://www.game-artist.net/forums/support-tech-discussion/13295-new-transfer-maps-maya.html

Images are in the post...

PredatorGSR

Yup, looks like you are using surface normals, switch to geometry normals in the bake settings and you should be good to go.

matr1X

Same problem with geometry normals mate. I think i need to cplit the uv edges BUT if i do that my texture will have a seam. It's like a catch 22 situation, cant have one without the other

PredatorGSR

Ah sorry, didn't look closely at your example. If you have hard edges, you need to split the uvs, if you soften the normals or bevel the corners (simple 1 face bevel will work), you can join the uv shells together. If you want to join the shells, beveling will give the best results because you have a 90 degree angle, so just softening the normals won't look good in a lot of 3d engines (though it will probably look good in the maya viewport).

matr1X

hmmm, im new to this as you can tell. I have just tried to bevel the low poly and the normal map looks better but it still has seams mate

PredatorGSR

Heh alright, let me show you. Either method works fine. In the shader make sure it is set to use tangent space normal maps instead of bump or object space.

matr1X

ok, smoothing the normals works best for me as i want to texture this and i need no seams in the uv's. However, i have another object that needs hard edges for the normal to work, soft edges doesnt, but i get the problem with the seam withought softening the normals on it. ahhh

matr1X

By the way, im actually following this tutorial;

http://cg.tutsplus.com/tutorials/autodesk-maya/create-a-new-york-subway-entrance-in-maya-day-2-uv-and-bake-2/

when he bakes his normals from high to low annd his uv's are sewn and normals hard edged, yet he gets the desired results. but im not and im doing it exactly.

PredatorGSR

matr1X wrote: »

By the way, im actually following this tutorial;

http://cg.tutsplus.com/tutorials/autodesk-maya/create-a-new-york-subway-entrance-in-maya-day-2-uv-and-bake-2/

when he bakes his normals from high to low annd his uv's are sewn and normals hard edged, yet he gets the desired results. but im not and im doing it exactly.

I dunno what to tell you, from the research I've done, mathematically it should be impossible to have hard edges and sewn uvs and not get a seam. If you have a hard edge, you need a different pixel for each split edge normal, and if the uvs are merged you only have 1 pixel. I don't know if there's much else I can tell you, those images demonstrate how to do it correctly.

matr1X

Yeah, i can appreciate that Pred but my only concern is the texturing. For example, i have another intricate object that if i smooth the normals i get a nice soft (seamless) edge but if i use hard edge it picks up the detail alot better in the normal map but i still have the seam on the edge. And with having separating the uv edges then surely your texture will have a whacking seam on it?

PredatorGSR

It's not really a big issue, unless there is a significant color or tonal variation seams aren't really noticeable if you do it right. If you don't have enough texel density, you usually get a subtle seam on the edges anyway. But the subtle seams aren't noticeable from normal viewing distance as long as your spec is fairly seamless.

matr1X

You have been great Pred, if i encounter any more probs i will ask

Thanks alot mate

kodde

I've come to the same conclusions as Predator mentions.

matr1X> Soft edges has the benefit of costing less triangles for a game engine. Once you use hard edges, material breaks or have a split in your UV your vertex will count as several.

From Guillaume Provost article "Beutiful, Yet Friendly".

The only way I can imagine getting away with hard edges and not having split up your UV's as you mention is if you do not use any texture filtering. It is the texture filtering that needs to sample the surrounding pixels that will otherwise screw up this scenario. This works properly with soft edges.