I’ve tried to make the mesh two-sided, honestly that made a lot of sense… but it didn’t fix the problem. Basically, the plank is made from a solid core, and the extremities are alphas on planes. With just the lighting applied, it look like this:
The opacity maps are as follow… I added the in-engine world normal map, as the normals connects flawlessly…
I also tried to remove all the alphas on the “interior” part of the plank, but that only slightly lessened the issue. Would there be a way to deactivate shadow casting but only on the alpha masks?