create lightmap atlases in Max

ajv3d

Hey everyone,

Any Max users out there know how to create different lightmap atlases ? ...and is it possible to have different atlases on one map? Even more so, what is an atlas exactly?

michi.be

Try Flatiron: http://www.texturebaking.com/
It unwrappes you the lightmap UV-Set in a decent way an you can use your mentalray light setup to bake all the stuff.

You also can set up a MR sun-system and render it to textures. There are lots of tutorials out there. Iwould use a script because I dont have time to bother a lot with stuff which can be automatted.

ajv3d

I've used flatiron before, it's ok. So I'm assuming lightmap Atlases are just the lightmaps themselves? I never heard the world Atlases used with lightmapping, that's why I asked. I thought it was something special.

michi.be

A atlas textre is a collection of several small textures on one large:
Like this: http://www.gamerendering.com/wp-content/uploads/textureatlas.jpg

It's for performance optimising.
So if you put your small lightmaps on a large texture for example 4x 512px on one 1024px you will get a lightmaps atlas.

ajv3d

Excellent definition, thanks man hahaha. I have a teency question about doing it though, are they completely separate lightmaps baked and laid out into a single lightmap, or just larger islands of of UV's specifically laid out to take up more space in the 2nd UV channel?

cman2k

In the case of lightmaps, the latter. These are larger islands of UVs from multiple objects specifically laid out to all fit into one 2nd UV channel.

ajv3d

Cman, you're all over these issues! Thanks man OK, so lemme see if I got this... atlas is really just a fancy word, and when someone is referring to an atlas they really mean a big-ass island? So I can....let's say for example unwrap the GROUND PLANE, and scale that bad boy up really large in the 2nd UV channel and that would be considered having "an atlas for the ground plane"?

cupsster

ajv3d wrote: »

Cman, you're all over these issues! Thanks man OK, so lemme see if I got this... atlas is really just a fancy word, and when someone is referring to an atlas they really mean a big-ass island? So I can....let's say for example unwrap the GROUND PLANE, and scale that bad boy up really large in the 2nd UV channel and that would be considered having "an atlas for the ground plane"?

NO

ajv3d

What's the workflow for creating atlases and combining them into a single lightmap then?

cupsster wrote: »

NO

cman2k

"Atlasing" is the act of combining many things into one UV channel.

An "Atlas" traditionally contains many different things in it.

If you take your example, and replace "Ground Plane" with "a bunch of different props that would normally be unwrapped separately", then your statement would be true.

ajv3d

...but I'm NOT unwrapping each object separately, I've unwrapped the entire scene into the same channel. The entire scene is on a single map...

cman2k

Even the 1st UV channel? This is unnecessary.

The whole idea is;
1st UV channel -> Unique UVs per object, different materials/textures and what not
2nd UV channel -> All Atlased to the same channel, all share one big lightmap

ajv3d

Nah, what you explained is what I have setup. I was just told to put props and ground plane on a separate atlas and I didn't know wtf an atlas was, let alone having separate atlases when my entire scene is on a single lightmap....

cupsster

then what you have is effective packing for one lightmap... you can make atlas when you need lightmaps of different density. that way if all props have their separate lightmap you can combine them to atlas to speed up rendering due eliminating texture switching in memory...
this can be done depending on your technical level right in max or you can combine them in your game engine via scripting to alter vertex data..
kapis?

cupsster

what you have been told is to have ground and props that have direct contact with it in same texture... reason for that is what I said above.

cupsster

reason for separate "atlases" might be texture budget constrains.. I presume that it is large area

ajv3d

That makes a lot of sense, thank you. So if each object has it's own lightmap (which is what I'm traditionally used to having inside of UDK) where can I find information on combining each of the maps to atlas inside of Max. There's nothing on the web, and this is something I would really wanna know. before you shoot me that is. *face palm*

cupsster wrote: »

then what you have is effective packing for one lightmap... you can make atlas when you need lightmaps of different density. that way if all props have their separate lightmap you can combine them to atlas to speed up rendering due eliminating texture switching in memory...
this can be done depending on your technical level right in max or you can combine them in your game engine via scripting to alter vertex data..
kapis?

cupsster

in max right now it's not so easy work but standard unwrap utilities or better texture tools by @renderHJS should help a lot.. It's just packing separate object (can assign unique ID before merge) of 0-1 mapping into resulted merged mesh.. Than you can have texture lightmap atlas generated via some helper function or manually tweaked.
if you make unwrap in flatiron for example, then you must somehow bring lightmap channel info back to your engine so you can map back to corresponding objects..
from my point of view is making texture atlas easier in engine of your choice, then just export geometry for baking.

Think of that squares as unique, more complicated separate objects..

ajv3d

I've been using TexTools 4.10 for some time now, I really like it, it makes life a lot easier inside of Max. I'm confused about how I can get each atlas to layout like the squares above. I'm assuming it has to do with the merging and setting of unique ID?