Creating a UV for tileable texture

Dethling

Hi Polycount,

I'm working on a bigger model at the moment (http://polycount.com/discussion/175397/raven-wh40k-imperial-fast-space-freighter) and want to use it to learn the use of weighted normals and tileable textures.

To learn the process I took one of the engines of the ship and already did the wieghted normals.

The problem is now the UV Map.
Is there any simple way to layout the UV for tileable textures (I want to reduce the amount of seams of course) or do I have to build every UV island by hand (relax, stitch etc.)?

I use 3DMax for modelling, Substance Painter/Designer for Texturing and want to get it into UE4 at the end.

Quack!

You will have to hand touch many pieces here.  Having beveled edges with face weighted normals will cause auto-unwrappers some problems.  In general, I would recommend setting your hard edges where you want UV seams to be, running a script that unwraps based on the hard edges, then clean up from there.  You can accept a bit more distortion in your uvs then usual with this workflow too.

Dethling

Damn. I hoped there is a more simple, more elegant solution to this.
So basically I have to create one UV island for every piece which should have the same texture and then arrange and relax it until the texture looks good...

ZacD

You don't need hard edges at all uv seams. You need a UV seam where a hard edge is. 

I would just put UV seams along natural seams along the model if you want to focus on tileable textures. 

McGreed

@Dethling
Remember that you can select all your meshes and apply an UV Unwrap to them and working with them all at the same time, this way you can snap your islands together and make sure they fit. However I do notice that 3DS Max UV Editor can get unstable when doing this, so remember to save often, especially if you use the relax tool.

Bek

ZacD said:

You don't need hard edges at all uv seams. You need a UV seam where a hard edge is.

Which is where, exactly, on a model using weighted normals? That advice applies when you're baking a normal map from a highpoly source, which is not the case here — or so I assume by the OP's statement about using weighted normals, and the wireframe showing so. I would also stress that the word 'need' needs emphasis in that case, or better yet, a proper explanation, because even though you might not 'need' a hard edge at a UV seam, it might make sense to do so anyway.

One thing to consider is that if you're not using an atlas of tiling textures, you only need to unwrap your pieces and scale them correctly — they won't need to be packed with unique space. So you save some time there. Though, you mention substance painter, so I take it the full project will have a mix of unique and tiled textures, in which case I'd also recommend using the former on repetitive pieces and the latter on large scale pieces. The logic being that repeated things benefit the most from the saved geometry of using lowpoly + baked normal vs. weighted normals, and the largest in scale the most from using tiling textures (less total texture size while maintaining high texel density).

So applying that to your concept, I would've considered having the engines as uniquely UV'd (and baked/textured) because there is four copies of them, and using the tiling textures + weighted normals on the large flat pieces. Not there there's a right/wrong way to do it; that's just how I would've approached it.

Dethling

Thanks a lot guys for the feedback, this will definitely help me.
My idea is exactly what ZacD mentioned, using a combination of both, tiling and unique UVs.
I'm not yet sure where I will draw the line, so which parts (size) will using unique textures and which will use tileable.
At the moment I'm thinking about everything bigger then 8 Meters (what is the rough size of the engine^^) will use tileable textures (to keep a 512px/meter texture ratio, while staying within a max 4k texture size).

I grabbed the engine as a test here, as they have some complex shapes but are not cluttered with to many details.
I think this will give me enough space to learn this technique and build up my workflow for it, which I then can use for the other parts, too.

I already unwrapped a few of the engine parts and while it's a little bit scary at the beginning, the results are good (will post them later here).

Again, thanks a lot guys and don't hesitate to comment on the model itself (and post any sort of feedback and tips^^).