lightmap baking

[ava]

Hello,

 

I'm trying to bake lightmaps in 3dsmax7 with the mental ray renderer. That works all nice, except that there are errors (black regions) near the seams of the automatically generated UV unwrap.

I'm using GI and final gather, and have the problem less with higher sampling, but I'd rather have no errors with low sampling. Anyone have a suggestion for this?

 

Thanx,

 

Alex

[nisus]

Hi Alex,

 

What MR version do you use?

 

nisus

[ava]

I'm using MR version 3.3. In the meantime I also discovered that it is not the renderer that causes the problem, but the fact that a small lightmap is used for a large surface. When using shadows this can cause light leaks as p. ex. in the attached file samp.jpg.

 

Possible solutions that I can think of: adapt geometry to these conditions or use larger textures.

[theqball]

Larger resolution should help some, but you could also try increasing the padding a couple more pixels if your uv layout has room for it.

[ava]

Indeed, and when I look at the automatically generated unwrap on channel 2 for the lightmaps I see that it would be better to do this manually. A lot of texture space is wasted.

 

Does there exist some good alternative to the automatic unwrap modifier of max?

[theqball]

Try to play with the RTT unwrap settings bit on a couple pieces to see if you get better results. I generally just unwrap them myself with unwrap UVW, but I used to do that crap day in and day out for a couple years so I get whip through them pretty fast. I could see where that’s not idea for a couple thousand objects.

In the Automatic Mapping rollout of RTT try using a higher threshold angle like 90deg if your objects are more planar or like boxes. Change the spacing to .005 or .001 to pack them in tighter.