The key to getting these very large hero props to look good enough for the player to walk right up to (or into, in this case) was to start with a Custom Normal (or Face-Weighted Normal) workflow – so I was mostly free from the limitations and time-consuming tasks of the baked normal workflow. The modeling process was pretty straightforward; I just had to be careful to make sure the UVs for the interiors of the meshes could be laid out perfectly flat and straight so I could handle the interior structural detailing with POM material functions.

After modeling, I spent time setting up a couple of master materials that could handle most of the large metal meshes around the scene with as little additional input as possible. For the largest props, I settled on a graph that would take a single channel-packed mask map made in Substance Designer and use it to define areas for the functions in the master material to appear. The functions that were laid down in the final material included:

two basic 1k Substances (painted metal and rust),

sand textures (already present in the layered landscape material),

two solid colors, used as either dirt or patches of paint.

As an experiment, the mask channel for adding the rust layer was used to generate a normal map using UE4’s built-in NormalFromHeightmap function to create subtle indentations in rusted areas. (This function is pretty expensive, so it may actually be more efficient to use a separate normal map generated in Designer along with the mask map).