Why am I getting these weird lines?

[jnrobinson]

I have a lot of experience with 3D modelling, but this is my first time trying to mod KSP.

I'm getting really weird reflections on my part when I apply edge smoothing with either blender (with the edge split modifier) or Unity.

The issue is visible in both KSP and the Unity preview window.

I'm just using a flat grey KSP/specular map right now.

I don't think my mesh is too terrible, so I'm not sure what's causing the problem. The weird lines show up in places where the mesh is a lot simpler as well (like on the other side of the cockpit where it's just a cone)

Thanks

[Dispatcher]

I've encountered that as well. Assuming its not a "feature" of the import/ export process, you might try adding more faces to the model, thus reducing the angle between them, which in turn might reduce or eliminate the unintended effect. Its not as if we are adding to the triangle count of, say, a character or complex parts.

[jnrobinson]

No luck. When the model has about 2000 tris I just thinner lines. It's really odd because they show up in very specific parts of the model in a way that seems to defy logic.

[Guest]

Is this happening no matter which of the KSP shader's you use?

[jnrobinson]

It doesn't happen in KSP/Diffuse or KSP/Unlit.

Is it common to use diffuse instead of specular maps for KSP?

[Porkjet]

maybe some normals are inverted or you have some doubled intersected faces or stuff like that? It must be some fault in the mesh. Does it happen on the other side too? If not, try replacing the faulty side with a copy of the good side. Can you show us a picture of the wireframe?

[jnrobinson]

maybe some normals are inverted or you have some doubled intersected faces or stuff like that? It must be some fault in the mesh. Does it happen on the other side too? If not, try replacing the faulty side with a copy of the good side. Can you show us a picture of the wireframe?

I don't think the mesh has any errors. The lines show up all around the model.

I modelled this part in Autodesk Inventor, exported it as an STL, then passed it through blender to get it into Unity. I've tried exporting the STL at a bunch of different resolutions (from 800 to 4000 tris), but that didn't fix the problem.

Here's a picture of my mesh, but I don't think it will be very useful because of the way I modeled the part.

[Porkjet]

I can't tell for sure from that picture, but it might be a problem with the edge flow.

Between those windows, I would expect lines connecting the two forming a quad in-between but I'm not seeing any lines there. This would mean you've got an n-gon there and auto-triangulation did a bad job on it forming extremely pointy tris with paralel lines. This is invidible on flat surfaces but screws up smooth shading on curves.

left is how it should be and right is what I believe to see in your mesh.

I've seen similar stuff many times after a mesh gets triangulated. You allways wanna make sure there are no n-gons and all the quads are 'cleanly' spaced. Lines that run much closer to each other than others around it on a curved surface will create a hard edge or those funky stripes.

But as said I can't tell for sure, maybe I talked nonsense. The backface lines make it hard to see in your pic.

[Dispatcher]

Did you try eliminating duplicate vertices in Blender, while you were in there? That could set you up for problems.

[jnrobinson]

You were right. There aren't any quads, but there are a lot of edges really close together in a bunch of different areas. I guess Inventor probably isn't the best tool for modelling. I think I'd spend longer cleaning up the mesh than I would modelling in Blender to begin with.

[Guest]

I have not tried to eliminate triangulation on any thing that complicated, but with simpler models, such as boxes and 6 sided polygons, you can select the entire model in blender's edit mode and then press f. This will eliminate triangulation and make solid faces. Then uv-unwrap, export uv layout, and apply texture in your favorite image editor. Next import texture in blender and ensure you have the results you desire by doing a render. If it comes out ok, save as .blend file. Then you can import into unity, which will triangulate faces again, but it doesn't matter anymore because the uv-map is done. I'm new to all of this, but it might be worth a try, especially if it keeps you from having to clean the model yourself.

edit : And I second on removing doubles in blender. This was causing me major headaches with my sketchup models. Once I selected the entire model and eliminated doubles, everything got much easier.

Edited March 27, 2014 by Otis