Workflow for UE4?

wonkza

I watched the official UE4 tutorial on materials, and I notices all the _Albedo maps also have an Alpha channel used with a "Lerp" node is used for the Roughness channel. 
But when I export from Megascan Bridge and select the Unreal preset, My _Albedo map doesn't have a alpha, but a seperate _Roughness map. 

Can someone explain me why those worlkflows are different and there is no Alpha for albedos out of Megascan?. I need to be as efficent as possible. 

Thanks,

Zack Maxwell

Megascan textures aren't made explicitly for UE4 in that way. You'd have to add the Roughness to the alpha channel manually in Photoshop.
It isn't exactly necessary, though. It's just a trick to save disk space.
If you're using additional maps, like Ambient Occlusion and Height, it'd be better to add the three of them together as a single third map, each mapped to a different color channel.

Maximum-Dev

Just to point out 2 things,
Adding an alpha to albedo doesn't save memory. Adding an alpha to a texture double's it's cost which is basically the same as having 2 separate textures.
And btw roughness has to be linear while albedo should be sRGB so basically roughness shouldn't be put into albedo's alpha (unless you counter that beforehand).

Synaesthesia

Yeah, I definitely wouldn't add roughness to the alpha channel. I always channel-pack my textures, so roughness is R, metallic is G, and AO is blue.