As this has changed obviously at some time in the past, can someone please explain to me which textures (including secret "save Satans fingerprint to Alpha of inverted normal maps" mambojambo) I need in which format named as what and saved to where to get a proper CUSTOM PBR terrain?

And which sources are needed / supported generally?

Diffuse / Color, Roughness, Gloss, AO, Normal, Specular ?

Color gloss normal ao and Metalness

You no longer add the specular map to the alpha of the color map, instead you use the "roughness" map called the gloss map in gameguru.
To avoid confusion, different tools and engines have different outputs for various textures, so we needed to decide on standard workflow for PBR and the outputs. So we are using the unreal engine workflow, in most cases the outputs a roughness map, which we call a gloss map in gameguru. Rest of the maps remain the same.

This basically shows how to add the specular map to the color map, just substitute the specular for the gloss map.
https://www.youtube.com/watch?v=3WnDfBjvWBM

Thanks!

Naming convention is the same like with PBR assets?
File Format PNG?

And where do I put the textures? I assign them via the texture painter menu lowright on the screen, I know that, but do they have to be in the texture source folder?

Place files here , Game Guru\Files\terrainbuild personally I haven't gotten around to creating terrain textures yet, but from what I can see the naming scheme is still the same with the format for the main texture being PNG and the rest DDS, other then creating the final color alpha, your guess is as good as mine, you would need to experiment a bit there.

Na, I meant if the textures have to be named _D _N (old school) -or properly _color, _normal etc

From the folder I can see it's _D _N ect......

hm yeah, but no AO or metalness there

I think it uses default metalness and AO maps here. Besides terrains in most cases wouldn't really need "metalness" in any case AO adds shadows in cracks and stuff so that wouldn't be what you would want any ways. I think the terrain shader was written specifically to only make use of normal, color and gloss.Will experiment my self over the weekend and finally do a terrain or two.

Ok, I get something that comes close to PBR look when following those guidelines - however, closeup, and especially against the sun looking (global spec influence) it turns into plastic. See screenshots!

But, honestly, I think we need a Preben or Lee here to answer.

Okay tried it my self, just mashed 3 random textures to make this with only one section with a glossly part, I can confirm it needs to be a gloss map, basically reverse of the roughness map we use for entities.
Normal map needs to be DDS.

Hope that sorts your problem

I spent a few days agonising over this very question a few months back when PBR was new. Not sure if they changed it since but I had some success controlling specular highlights by altering the alpha channel of the texture and saving as DDS. Didn't even bother to use a normal map or naming suffixes but it worked.

AE

getting there...