Lightmap Unwrapping Best Practices/Unwrapping Questions

[Chihuahua]

Hello, I have recently begun to create my own assets in UDK, but have repeatedly ran into the issue of the lightmaps looking less then desirable even on higher settings of both the static meshes lightmap resolution, and the production quality of the lightening. Now, I don't know if this is me simply holding to high of standards and not understanding the engine, or if I'm doing some wrong with the unwrapping tools in blender. Here's an example of the asset being lit in the standard renderer using play in editor, the texel lighting shown via a floating viewport, and the lightmap UVs from the Static Mesh Editor. The lightmap resolution is 32 and I believe it is on medium quality lighting. I'm also curious as to what is generally considered the "best" unwrapping program for something like commerical use, as using Blender's built-in unwrapping tools feels very frustrating, especially on flat, planar pieces like this. Thank you in advance for taking the time to read this.

[darthviper107]

32 is your lightmap resolution---that means 32x32 is your actual pixel size, so clearly that's a very small amount. The lighting quality is simply for rendering, it configures how much light bounces and how realistic it is.

For something like that I'd probably start at 256 for your lightmap resolution and go from there.


For making the lightmap UV's, the best way is by hand then you can set things exactly the way you want, and really use the space--ideally you minimize the seams as much as possible.

[JessieG]

You'll want to bump the resolution up for starters. 32 is good for smaller props but things like walls benefit from bigger resolutions. Try bumping it to 128 and see if that helps.

For the UVs, i can't quite tell if the triangles are too bunched up or if that's how it was modeled. But the general rule of thumb to follow would be to have the smallest amount of separate UV islands as possible (you have just one so that's good. And leave a bit of padding between each UV island as well as the edges of the 0-1 space. Also make sure nothing overlaps or goes out of the 0-1 space.

As for programs to layout UVs, I'm sure googling for plug-ins for Blender might help, but I use a stand alone program called Headus UVLayout and Maya so I'm not too informed on that. Headus is not free, but it's an amazing program and really speeds up my work flow so it's worth it.

One other thing to keep in mind is not to have too large of a mesh as one piece. Say for instance you combine windows, doors, and two floors worth of walls, ceilings, etc. into one mesh. That would mean you would need to pack all of those UVs into the 0-1 space without overlapping which would make every Uv island very small, requiring much bigger lightmaps that still may look terrible. Keeping objects to a manageable size and reusing meshes will give you more UV space for your objects resulting in better looking lightmaps.

[Chihuahua]

Hi, thank you for the quick responses! Bumping it to 128 did the trick, I'm much happier with the lighting, and surprised no tutorials really mention that walls should be much higher (most tutorials say to keep it at 32, 64 or 128 at the very maximum for what I assumed was all cases). I'll try Headus UV Layout, which I've heard a little about. I'll take your advice about small meshes as well. Thank you both!

[Chihuahua]

-Double Trouble-

(Sorry!)

[JessieG]

Generally the bigger the object (complexity mostly, not necessarily JUST size) the bigger the lightmap. Some objects in some of my scenes will have 256 or even 512 for the lightmaps. It just depends on the size/importance of the object. Don't be afraid to bump up the res every now and then, but don't go overboard either as you may run into memory issues and longer light building times.

[Paya]

I would recommend worldofleveldesign.com section on lightmaps.
It is very good and most thorough.