UV Unwrapping Tips and Tricks

[CaptainKipard]

What is your preferred format?

OBJ is fine.

You can offset overlapping islands by 1 in U or V, and leave only one island in the 0 to 1 UV space and everything will bake just fine without W-fighting artifacts.

Could you explain this a bit more? I'm not following.

[nli2work]

Some times you get artifacts when you have overlapping UV patches all set to same W; just like you get Z-fighting with overlapping faces. usually this happens when you mirror geometry You can offset all the patches except one set, by integer distances in U or V direction to avoid getting those artifacts. By default UV space is tiled infinitely in both directions so as long as the islands are offset by integer distances they get the same texture. only exception here being maps set to clamp instead of tile, but that's in specialized situations like cube mapping skybox.

[noonespecial]

OBJ is fine.

Here you are.

[noonespecial]

So, any luck with the UV unwrap of that model?

[CaptainKipard]

I'm sorry this is what happens when you're juggling projects. I promise this will be the next thing I do.

[noonespecial]

I'm sorry this is what happens when you're juggling projects. I promise this will be the next thing I do.

No worries mate. Take your time.

[CaptainKipard]

I'm making my preparations. I'm not sure how to proceed. There's a lot of unnecessary geometry in that model. Some of it is completely inside other geometry, which means it's completely invisible. Some of it is nearly coplanar with other faces, making it only partially visible. The strut ends are not needed. The larger tanks clip through the struts.

In terms of immersion the tanks don't look attached sufficiently to anything.

All of these things make unwrapping a bit more complex. It pays to plan ahead like I said and that planning should really be part of an unwrapping guide. It's all very closely linked. Would you like to start over and make a tidy model? It's not hard at all to make things mathematically perfect. You don't even need to calculate anything, as long as you know how to make good use of the scale, mirror and array tools. This model is IMO a lost cause. It would be a lot less effort to make it from scratch, especially if you want to use it for a tutorial, and especially because it has a lot of symmetry.

Edited October 24, 2014 by Cpt. Kipard

[noonespecial]

I hope you don't take this the wrong way, because I do mean it with the utmost due respect.

But, concerning your comments, I'm not sure you fully understand the workflow I'm using here. This isn't the first time you've mentioned "planning ahead" and how important that is to unwrapping. If you understand the workflow I've used here, you'd understand that this method would impossible without planning ahead and is probably the reason you're having difficulty trying to unwrap this model outside of it's planned workflow.

The design, as shown in the tutorial, was heavily planned with the UVMap and texture in mind. Thus, the minimal number of parts and how those parts are constructed and unwrapped before being duplicated and building the model "lego" style. The UVMap for this model is actually extremely simple when following this workflow, resulting in 19 unique islands. Unwrapping this model outside of this workflow would result in nearly 300 unique islands. Here is an example picture, showing the UVMap, texture, baked AO, and normal map of this model and the completed model in KSP itself.

Additional comments: Unless there is some error in that file or it was imported incorrectly, there is no geometry that is "completely inside" other geometry. The ends of the struts clip into the joints, but that's about it. Other parts may pass through pieces of geometry, to minimize face count, as visually and structurally there would be no way to tell the difference without dissecting the model.

"The larger tanks clip through the struts." "the tanks don't look attached sufficiently to anything". The tanks are connected, flush, at the top of to the hexagonal plate that is the top of the lander. The tanks are connected, flush, with the storage boxes at the bottom of the lander. As you say, the tanks clip through the struts, as seen here.

Which is essentially a low poly "the strut is welded to the tank". Thus, as the tanks are connected above and below, as well as with struts, I do believe it is sufficiently attached.

However, I will say that your misunderstand is partially my fault. The model I provided you was not the "completed" model as shown in that picture. The landing legs and storage boxes are animated and were separate parts added to the final model in Unity. I probably should have explained that. The landing legs model adds additional support to the smaller tanks and the storage boxes fill in the void left in the lower portion of the model as shown here.

[CaptainKipard]

Could you upload an unwrapped model?

[noonespecial]

Here you are. Still minus the animated parts.

[comham]

This is really handy, thanks.

[trekkie_]

If you're texturing 20 different spheres separately, you're doing something wrong to begin with. any copies of a model should be textured before making copies. and texturing a piece of a cylinder and making copies of it, is not going to work for anything but completely symmetrical models, which in that case, is much easier done wrapping a texture around the whole thing by repeating it along a vertical or horizontal axis. if there is a seam issue, all one must do is slightly increase the size of the texture on UV, and then pull it toward the seam ever so slightly. and AO baking is really only good for 3d rendering, since it's environment dependent. It has the opposite effect by making lighting look less realistic in environments other than the original.

Edited November 29, 2014 by trekkie_

[jandcando]

This is valuable information... I'm extremely glad I discovered this sooner rather than later. Thanks!

[zilfondel]

Wow, this was so informative. I just created my first blender model a few days ago and spent an inordinate amount of time texture mapping everything, but then realized I can reuse textures in the UV map. Thanks for the tutorial.

Now I just need to figure out the basics in blender more.