UVs and lightmass

L1151502

Hi Guys
Im fairly new to UDK and making a small environment for uni
Im curious
will overlapped UVS cause an issue when i bake the light using light mass? this is in regards to say a wall and both the front and back face UVs being overlapped

Thanks for you'r time

Jacky

Yes they will. You need to create a second UV channel for lightmaps with no overlapping UV's.

L1151502

Ok Thank you

L1151502

sorry can i just check when you said light maps my question was refering to light mass and baking the light in UDK not when producing a light map AKA AO bake
is this what you were also refering to Jacky ?

James Ordner

You can leave the first UV channel however you like, overlapped, outside the 0-1 space, etc. However, if you want to use lightmaps, you need to create a second UV channel with no overlaps and all UVs in the 0-1 space. The regular material/textures will use the first UV channel, and the lightmaps will use the second UV channel.

Jacky

When you build lights in UDK you actually render lightmaps for static meshes in your lvl, so it's not only lightmass related.

L1151502

ok thanks very much guys.
so my final question is if i have optimised the unwrap for the diffuse by say unwrapping both a fire alarm and a wall onto one 1024 x 1024 sheet, and have made space for both assets in the UV space by overlapping UVs. Would you then suggest that i create a separate unwrap for each assets light map (EG 1 x 1024 for the fire alarm and 1 x 1024 for the wal.)

Or would industry practice sway more towards fitting all the UV islands into one 1024 for the light mass also

I apologise if these seem like simple questions but im really new to UDK

passerby

just unwrap each prop into the full uv space for lightmaps, udk will actually choose the appropriate map size, and it will make a texture atlas out of hte lightmaps of multiple meshes on it's own.

WarrenM

EDIT : Oops, never mind, I misunderstood.

L1151502

thanks a lot guys this was really useful and has saved me a lot of pulling my hair out
really am greatfull.