Problem with normal maps seams overlay

NAIMA

Hello , I have created a normal map for my furslips model and looks fine on all seams , in xnormal , but then I needed to add fur details , so I painted fur on the "furry meshes parts" in mudbox and then I used flaming pear plugin to expand the texture beyong the seams , I then took this partial fur texture into Crazybump and I used to create a normal map of the furs out of it , it looks all god except for the seams when I overlay the map over the other original base nrmal map , the seams look evident after this merging ... what can this be due to and how could I fix?

cptSwing

a picture would help!

- are you viewing the result in xnormal or a different viewer?
- did you overlay "correctly", knocking out the blue channel at least?
- swizzles..?
- ...

NAIMA

Here are some pictures ....



As the Red arrow show , the left version is the normal map same as the right one but I have overlayed a fur normal map extracted via crazybump from a textured version in Mudbox , the texture itself is seamless in mudbox , so I wonder why it is not in normal maps?

as for the overlaying I just did "overlay and deleted the portions of the normal that overlapped the other normal maps parts of the map under...

Bal

When you're converting with crazybump there's no information on the direction of the faces from the lowpoly, so it's pretty much unavoidable that you'll get some seams where you have UV splits.
Check your crazybumped normal map alone, to see how visible the seam is, if it's alot less visible, you should look into how you're overlaying your 2 normal maps, check the wiki for better methods :
http://wiki.polycount.com/NormalMap#Blending_Normal_Maps_Together

NAIMA

is it possible to use the texture mapped on the model and make a normal map extraction from the model in crazybump? or in xnormal so that it keeps the informations on seams?

Noors

Overlaying 2d textures on a bake has always been a mystery to me. It's fine for a tile, where directions are explicit but there's no way it could be correct when uv are rotated, flipped, distorted.

imo, most of the time those kind of details are sculpted in HD, and only a sort of high frequency detail map is added in 2d, so the seams are almost not noticeable.

I was thinking that maybe using a detail texture as bump on a low poly, and bake a detail normal from it could do the trick. Thoughts ?

Yeah we need a software a la crazybump which creates a map considering a mesh normals/uvs

passerby

what game engine are you using?

in some engines you could apply the overlayed normal map in the shader, and use worldspace coordinates to project the detial normal on the model instead of relying on the UV's that have seams.

cptSwing

you can include detail normal maps in your xnormal bakes

Noors

aw, and does it blend according to uv direction or is it just a "simple" overlay aswell ?

NAIMA

What woudl be the use for detail normal map in xnormal? I specifically avoided to sculpt brush out the fur in the slips couse I tought to add a more detailed / matching to photosource texture with crazybump , is not that the seam are all that noticeable and I could hide them with an extra polygon shape in alpha texture but I am wondering if I can make it "perfectly" seamless somehow using the basic shape normals form the sculpt in zbrush and the added in fur normals from crazybump ...

or may be I should transform the texture into a alpha texture map and apply it on the fur parts in zbrush then extrude or brush out but I don't think woudl come out that well ...may be I coul djust go and create some alpha brushes for zbrush and make the fur in the model directly but then I am not sure how to give the "realistic " random colors of a real fur then in the texture and achieve the same level of detail ...

Oh btw thew game engine it is destined for is the not so advanced skyrim engine so doesn't have all the nice blending functions of UDK or other material properties of Cryengine ....