Normal Mapping Question

[Affuso]

No , In Carrara I put the low and the high poly meshes , without NM.
I known that Carrara can use a plug in for NM , you can't use it without this.
I do not purchesed it , yet.
I need Nm for my game models, for make them...less ugly.

About my models: the low have uv coordinates

[jogshy]

Originally Posted by Affuso

About my models: the low have uv coordinates

Your UV's seems to be overlapping. The triangles should have an unique texture space assigned ( except if you mirror UVs, which is an advanced thing and not all the 3d engines supports NM mirrored ). See the xNormal PDF docs about that "UV overlapping" on page 35 "2.4.2 Problems with T-junctions and overlapping texture coordinates".

This process is called "UV texture uwrapping" and is crucial to make good maps. See these tutorials about how to UV-map well an object:

http://www.oman3d.com/tutorials/3ds/unwrap_uvw_mapping/
http://wiki.blender.org/index.php/Ma..._the_UV_Layout
http://www.maxforums.org/thread.aspx?tid=435046
http://www.ramyhanna.com/texturing/p...utorial01.html

[philip_ho_]

thanks for the quick tutorial jogshy, i did what you said and this is what i came up with.
there are some bits that i dont know how to get rid of for the normal map, thre seems to be some sort of distortion in map but i dont know hot to get rid of it.
any tips?

[jogshy]

Now you need to measure a good ray distance. Those artifacts are caused by ray failures. See the PDF help section "mesasuring ray distances". As a quick approximation use a 3dsmax "tape" helper or radius divided by 10 ( and sure you check the "closest hit if ray fails" option ). You need to play with the ray distance parameters until you get decent results ( can be hard ).

However, the uniform ray distance approach usually is not perfect. In fact, I don't like it at all.
I recommend you to use the alternative "cages" method which gives the best result by far. Unfortunally, it's not easy to setup. For a small theory explanation you can see Ben Mathis cages theory tutorial at
http://www.poopinmymouth.com/tutoria...l_workflow.htm

Here you have two options... To use the xNormal cage built-in editor or to use an external cage made with, for example, Maya. See the xNormal's Flash tutorial about cages in http://www.xnormal.net/Tutorials.aspx

Assuming you want to use the build-in cage editor do this:
Sure you have the SBM highpoly and lowpoly assigned in the correcponsing mesh list slots.
Basically enter inside the xNormal 3D viewer. Check the "show cages" option. Extrude the cage until the highpoly model is COMPLETELY surrounded by the cage. If you need to tweak a vertex selection use the "edit cage", select vertices and move them. Once you are happy with your cage click in the "Save meshes" button and save as SBM ( the SBM is the native xNormal format, which is farter to load and saves the CAGE INFO inside ). Then, exit the viewer, reset the settings and select with SBM highpoly and lowpoly files on the corresponding lists. On the lowpoly mark the "Use cage". Generate maps.

Assuming you want to use external cages:
Enter Maya/3dsmax/whatever. Clone your lowpoly mesh. Extrude vertices until the highpoly is fully covered with the cage. DONT remove/add faces to the cage, the topology of the cage must correspond EXACTLY to the lowpoly mesh. Save cage and lowpoly mesh in the SAME format(for example, OBJ).
Open xNormal, reset settings. Put the meshes on the list. On the lowpoly one browse and assign the external the cage. Generate.

Also, to maximize texture space usage when using tangent space normal maps ( and if your 3d engine supports it ) try to use UV mirroring, but caution with the symmetrical-face-look-syndrome!

I'm not an artist but I thing faces are usually UV-mapped frontally and sides near ears cylindrically. I think 3dsmax has a modifier called "Relax UVs" and "Unwrap skin" to help too.

Finally, I recommend you to plan very well the UV seams in a way that would be hidden by the hair.

Hope it helps

[RedSquare]

Oh dear! so much to learn.

[philip_ho_]

ok so now i've done the cage method its got rid of all the gaps and stuff now but another probelm has come up. its not as smooth as what i had before, this time all the faces can be seen on the map too. Why is this? if u could help me with this one too it would be much appreciated

[jogshy]

The exporter saved bad the vertex normals ( or the smoothing groups ). Did you forget to check some option in the exportation in Maya/3dsmax/whatever you use?

That can be in the lowpoly mesh or in the highpoly one:

For the lowpoly one, you can check the option "Smooth normals" ( in the lowpoly mesh list slot ) in xNormal to solve this quick, so the vertex normals exported will be ignored and xNormal will calculate the vertex normals ( of the lowpoly model ) for you.

For the highpoly one you need to export the mesh model without normals if you want xNormal to calculate them. If you export the highpoly model with normals then will be used ( perhaps is that what fails, the highpoly normals are bad exported )

Hope it helps.

[Affuso]

Interesting, the higpoly mesh must does not have Uv coordinates?

[jogshy]

Originally Posted by Affuso

Interesting, the higpoly mesh must does not have Uv coordinates?

No need ( unless you are baking the highpoly base texture into the lowpoly mesh ).

On the other hand, UVs on the lowpoly are required always.

[jogshy]

Added a new tutorial about how to export cages/meshes from 3dsmax 9 using the new xNormal SBM mesh exporter.

It's at http://www.xnormal.net/Tutorials.aspx as usually.
thx