Thanks to the docs, I managed to get realistic skin and grass working. For a lot of environmental materials, I can use the default ones for inspiration and they look good in-game when I copy and swap the diffuse textures.
And the above is a pair of tracksuit bottoms. The reference photo was from my Adidas tracksuit bottoms.
The problem is that they’re both too fabric-y and not subtle like real-life clothes are. I want it to be a tad brighter and for the bumpiness to be apparent only in a close-up. How can I go about doing this?
When you say they are from photos, does that mean you converted the photos into heightmaps using some program?
Not seeing your reference photos makes it hard to comment on what is different specifically so I will have to speak generally. The cloth pattern on both the shirt and pants seems abnormally large, more of a burlap material than typical modern fabric. Also the roughness looks way too low, especially on the shirt. You shouldn’t really be able to see a specular highlight like that on fabric. Makes it look rubbery.
I suggest using an independent tiling pattern to represent the fabric normals. The texture can probably be really small as long as it repeats well. Then in the material, create a scalar parameter for the fabric normal tiling as well as a vector parameter for the normal strength. Then you can really tweak the pattern to match reality better.
Also look into using the subsurface or twosidedfoliage lighting models. Fabric is always going to let a bit of light through. You can even get creative and use a separate texture for the SSS mask. The kite demo has a great example of that kind of material, although the kite itself is more of a tarp like material rather than cloth.
If you have not checked out the Kite Demo give that a look as the boy character in there has clothing that looks similar to what you are trying to achieve.