HowTo:FullUnwrap2Clean

Cleaning up the mesh (Part 1)

First of all you need to make sure that you are 100.00% happy with the mesh. Not 99.99%. Why? If something shades funny, you won't be able to "fix it" with the texture, --other than by painting it matte black, that is; but you probably don't want to do that. You need to find your errors and fix them all. Typical mesh errors are split polygons that you didn't mean to split, non-split polygons that you did mean to split (read the tutorial on smooth groups, if you don't know what I'm talking about), missing polygons, inner polygons and edges shared by 3 or more polygons, free floating edges with no polygons... You need to clean all that crap first. One very useful trick is, from the Edit mode Select menu: "Non-Manifold". It's hard to explain what it does, so try it and get used to it. All mesh edges and splits will be selected, so you can make sure all your sharp edges are indeed selected. And if you find any edges selected that you didn't expect selected, they probably have coplanar or inner polys. It will also help you see missing polys. Another thing you should do is unclick the [Double Sided] button, to make sure you catch inverted normals.

If you work like I do, you probably have one or two dozen objects spread through half a dozen layers. For unwrapping we'll have to put it all back together in one piece. Well, two pieces really:

1. The big parts
2. The tiny parts

How big? How tiny?

The tiny parts are those parts so tiny we don't even care to texture them. In this case, all the hand-rails and ladders. What? You can't see them? Well, you shouldn't be able to see them. Let me get a close-up shot. Hold on...

Here. Notice the ladder, bottom left, and the scaffolds at the top?

There's scaffolds at the bottom also. I just added a couple of yellow lights to make them more visible.

Not saying you should have ladders and scaffolds; I use them as a way to give players a way to judge the size of a ship. Windows help also.

In any case, I was saying I don't care to "texture" the hand rails and posts. They are too thin for even one pixel. Well, maybe not too thin for one pixel, and perhaps them being illuminated by yellow spotlights might look good... Okay, forget it; we'll unwrap everything. Except the subunits, that is: The gun turrets, for example, will be sub-units, because they have to be able to turn. So they'll have their own texture. But we still keep their geometry, because we need their shapes to cast ambient shadowing during our bakings. So, we'll leave them in, but put them into a separate object that we won't UV-unwrap. Anything else you don't want to unwrap, put it into the separate object.

So, other than such exceptions, we want to have the whole ship be a single object. But now, chances are you may have scaled or rotated some of your objects. Chances are some are mirrored in the Y axis; --not just the X axis. Some may have a sub-surf modifier. Some may be curves (like pipes, for instance) rather than meshes. And some objects may be things you put there and meant to clean up later but forgot.

So, first you need to go object by object ... Best way to do this is by clicking on one object at a time in the outliner window; that way you don't miss any...

(Full Size)

...and for each of them you apply any attributes other than X-mirroring, click on Center Cursor (assuming your cursor is at the origin; otherwise send it there with Shift-C), and then Ctrl-A to apply any scalings and rotations you may have done in Object mode. Otherwise you could have your normals all messed up (scaling and rotating objects in Object mode doesn't recalculate the normals until you apply it to the mesh). Then Shift-Right-click on the main object and Ctrl-J to join them. Once you're done, you'll have a single object.

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