I can’t explain every step of this, but there are some features that are worth talking about.

Albedo brightness: You would not need this adjustment parameter if having a perfect albedo, but when using photogrammetry, the brightness of the color texture depends directly on the light conditions when capturing your subject, so a bit of adjustments inside the engine is always needed. To work around this problem upstream, you can shoot your photos in a indoor studio, or using different techniques like HDR & greyball de-lighting, but this was not my case.

Detail normal : this is a tileable normal map used to create some little detail on the surface. Why is this needed? Because if I wanted to achieve this detail with only one normal map (being able to get it through the photogrammetry) it should be too big (like 4k or 8k) to get the same detail as if using a tiled detail normal blended with the baked one.

At GDC 2016 DICE did a very detailed breakdown of their photogrammetry pipeline, from whom in the past I learned a lot. If you follow this link from slides 75 to 91 they talk about texel density and performance issue. I don’t want to repeat what the masters have said, so if you are interested in how they used detail maps just read the whole thing.

To blend the baked normal with a detail normal you have to add them excluding the detail blue channel. I also used the Object Radius node to maintain the coordinates relative to the Rock radius. This way I can scale the rock without having to check the texel density again.