I’m currently re-thinking my workflow for asset creation and have a question I hope you guys can answer. I have been seeing the use of “mask” maps which include AO, Gloss/Roughness and Spec/Reflection maps. I’ve always baked my AO into my colour maps to create a diffuse map, doing this uses up more UV space as you can’t use overlapping UV’s for areas that will have different AO information.
My question is what is best practise? Create a second UV channel for the AO information so that it is combined with lightmap information?
Everyone will have a different method for dealing with AO maps and by no means am I saying this is the best way of dealing with them, but I have found excellent results from this method. In UE4 you should be doing a second unwrap for lightmapping purposes anyway, so I tend to cook my AO maps to that unwrap and then using a texture coordinate in the Material editor set to the second UV channel (Channel 1 as UE4 defaults to CH.0 and Ch.1) multiply my diffuse by my AO map. Of course this is another texture sample and that can add to the complexity of your shader, but I will typically try to greypack (store in one of the RGB channels) my AO map with a transparency map or another element to reduce the total number of textures used.
Also depending on the complexity of your model, the engine also has an amazing AO system built into the lighting but your model has to have the geometry.
Thanks for your reply! I see what you are saying and I like the method you have stated as it was something similar to what I was planning on using. Yea I normally setup a second UV channel for the lightmapping so using this for the AO as well, sounds like a good idea to allow saving of UV space in the first UV channel, will also give greater control this way too.