Static mesh rendering problem

[edx76]

Hi there,

Here is the problem:

I modeled a rock in Sculptris, textured it with the texture painting tools, reduced the number of polygons and exported the mesh (in .obj format) and also the diffuse and normal textures.
Then I converted my .obj mesh to .ase, using blender.
Then I imported my .ase mesh in UDK, I made a simple material with the diffuse and normal textures. My diffuse texture is connected to 2 slots: diffuse and specular.

In the static mesh editor, my rock looks fine:

[IMG][/IMG]



So I put my asset in a simple level with one point light and you can see it looks crappy.

[IMG][/IMG]


Seems like there are some lighting rendering problems in some parts of the texture.

Why is there such a difference between static mesh editor vizualisation and game? And how could I fix this?

The only thing I found so far is to disconnect my diffuse texture from the specular slot of the material: then it looks good but, as there is no more specularity, the relief effect provided by the normal texture is very small. So it is not a real solution.

[dalewb]

I believe the SM editor window has one or two point lights in it and that's it. Plus there are no surfaces in that window for the light to bounce off of. In your scene, you placed your rock on a surface and stuck a point light above it and then did a build all, I assume. Well UDK uses lightmass when you build your lighting, which simulates bounced lighting. The one point light in your scene is sending rays that bounce off the surface beneath your rock and hit it in a million random places - basically all over it, and from various directions. Depending on how you modeled it and unwrapped it, you might get ugly seams in places if you're not careful. If the rock will always be in that position, you might try adjusting the unwrap so most of the seams are around the bottom, shadowed part of the rock.

[edx76]

Thanks for your reply
Yes, the problem came from the seams I choosed to mark to unwrap my model.
I unwrapped it another way - with the seams at the bottom and there is no more problem.
What I wonder now is:
- what if you cant solve the problem this way? For example, for character texturing, you need to mark seams here and there, you can't "hide" the seams.
So, are there any tips, any rules to avoid the problem?
Are there any docs or threads I missed on this subject?

[dalewb]

I'm definitely not an expert here, but UV seams can be hard to hide. In character models, the seams are hidden in less obvious places, like the underside of the arms, the back of the head, etc. You just have to be clever about it. Sometimes you can paint the diffuse in such a way that the seams are less obvious. Overlaying the "wires" from the unwrap can help do this. In any case, it's an arcane art and I'm still learning - I believe you only get better at it with practice. There are books that might help as well, such as 3D modeling for games.

That's a good-looking rock by the way :-)

[Ghiest]

SM viewer is dynamic light and obviously baked lighting is not.

With baked lighting you must remember that all UV seams are counted as Hard-edged (in terms of edge smoothing / smooth groups).

[Hitpawz]

Make sure you import your normal map with Normal Map compression set on it. Also, it appears as if you have it, but you should include a specular map. I used to have a huge problem with UV seams until I realized the compression and specular map conditions. Now it pretty much doesn't matter where I split my UV's, the lighting is consistant across the entire object. Also, I usually just use my diffuse as my specular map. If you need the object to have little to no specular, then just multiply it by a # close to 0.

[edx76]

Ok, thanks a lot, guys, for these informations and tips.

[radomiro]

Make sure you import your normal map with Normal Map compression set on it. Also, it appears as if you have it, but you should include a specular map. I used to have a huge problem with UV seams until I realized the compression and specular map conditions. Now it pretty much doesn't matter where I split my UV's, the lighting is consistant across the entire object. Also, I usually just use my diffuse as my specular map. If you need the object to have little to no specular, then just multiply it by a # close to 0.

But is needed a second uv set for lightmap yes or no?

[dalewb]

YES. You can do it manually in your 3D package, but I found the utility in UDK's static mesh editor to generate unique uvs is much faster and easier. This allows the game to bake lighting onto your static meshes so shadows from other objects in the scene will fall on them as well.


The default settings work just fine and don't harm your mesh - just click the accept button and you're done.