Multi Mesh Complex Mesh - Lightmass

zombieminteractive

Hello all.

I am in need of help with getting the light mass uv channel to work correctly with a mesh with multi meshes.

After unwrapping all my meshes, and doing every ones "light mass" uv I get problems after getting it in the udk.

When importing with the "combine object" on the uv channels get mashed up into one uv (1 for defuse, one for Light mass). While the defuse channel works, the light mass channel is broken.
I came to this conclusion by building my mesh with each object by itself and having the normal maps all of a sudden work.

can anyone help?
:poly118:

Radiocity

Have exactly the same question

WarrenM

The UVs for the lightmap have to be laid out uniquely ... like, with no overlapping. Are you saying you're doing that but it gets wrecked when imported?

zombieminteractive

I make my mess, then unwrap each objects uv , then its lightmass channel uv.

When I import this (export scene or selected) into udk and import it I go to the mesh options menu and look at each channel. It "combines all the uvs into one" but the only one messed up and having issues is the Lightmass not working, where the defuse works perfectly even when showing the uvs all combined.

r4ptur3

select all your meshes in your modeling package and treat them as one piece when you UV for lightmaps. you are going to have to shrink the UVs down quite a bit. Everything needs to be uniquely laid out -- if you select all your meshes and see overlapping UVs in your modeling package the lightmap will fail in UDK.

zombieminteractive

Oh so when I am m unwrapping them take into account the other uv unwraps.
Example I put a box in the upper left corner, in other unwraps don't have anything where that uv unwrap of the box is at?

zombieminteractive

Also, if I unwrap say a loop of a chain then Instance the next one will I have to re-unwrap that to not overlap?
I know it sounds nooby

r4ptur3

yep, you got it. it's confusing for sure. instanced geo will need unique UV space as well.

Radiocity

I have a ask I downloaded a Textured model from Turbosqid. The model look good, but the UV's are just total messed up. If the UV's are super ultra messed and overlapping is it even possible to create the seconed UV channel ?

Edit I think i found a way to fix this automatically But not best result but for a big model with messed up uv's i think its works

zombieminteractive

This would only be for the lightmass channel correct? Since the defuse channel does not mess up?

r4ptur3

The diffuse channel (1st channel) can overlap and do whatever you want but the lightmap UVs (2nd channel) need to be unique. They should not have an effect on eachother

zombieminteractive

r4ptur3 wrote: »

The diffuse channel (1st channel) can overlap and do whatever you want but the lightmap UVs (2nd channel) need to be unique. They should not have an effect on eachother

Thanks for all the help. Would the 2nd channel uv's being slightly smaller then what the defuse is cause any major issues with the detail of the lightmass pass?

r4ptur3

you should be ok -- you can open your mesh in the mesh inspector (double click in the content browser) and specify the lightmap resolution. It defaults to 32 pixels so you might need to up it for more complicated meshes.