Today I was browsing the web for any information about how to create textures with Gimp. I didn't find any information regarding Gimp, the only information was about Photoshop, and apparently PS does not load a Fallout 4 normalmap correctly, which does not sound promising in regards to Gimp . I decided to test whether Gimp works, and so armed with the newest version of Gimp and the dds-plugin (which hasn't been upated for ages) I dared to open a Fallout 4 normalmap.

And to my shock it was working out of the box (Gimp displays normalmaps as they are also displayed by WTV, and they also look like normalmaps are supposed to look).

As next I tried to get textures and normalmaps created by Gimp into the game. And again it was working out of the box . You just need to select DTX1 for diffuse textures and 3Dc for normal- and specularmaps when exporting.

At last I tried to find out how PBR was influencing texture creation. PBR introduces two new parameter, usually called metalness and roughness (mor information http://jmonkeyengine.org/299803/physically-based-rendering-part-one/). They seem to be encoded into the color channels of the specular map (red and green are used for that, blue and alpha are unused?). I experimented a bit with specular maps, and I think that the red channel is used for metalness (the higher the value the more metal), and the green channel is used for roughness (the higher the value the smoother). I would post screenshots for proof, but apparently I cannot find the attach-picture-to-post button.

I'd be interested to see this. Unfortunately we don't allow image embedding on the forums so you'll have to use a third party image hosting site like http://imgur.com/

You saying the devs were drunk?

Sorry, couldn't resist.

http://imgur.com/a/NH5Ul

Sorry, don't get the joke.

http://imageshack.com/a/img911/2007/s92xpB.jpg

Yes I was more than just happy to find the old GIMP DDS plugin worked, as you say changes made to existing DDS files work, it saves and creates the MipMaps just the same as all previous games.

Not tried the Normal Maps plugin as yet but there where comments that the Normals may have issues with the Unpacker? That may have been for dropping the original Normals into a loose folder

situation? Very glad to see your getting success with those as well, not done that much yet just small changes to some grass colours and I hope to look into some of the blander dull armours.

Interesting. You should try changing your specular channel to a brushed steel kind of texture! It'll look more metal and plastic dipped.