Argh! Apparently, Lux does not like to UV-map quadrangles. I'm not completely sure what it does, but from the examples I rendered, it seems to just smash the complete texture on every single quadrangle. Triangles seem to work fine, though.

Also, it looks like Lux flips the V axis relative to Poser. I need some more tests, but I think I am now really close to getting the UVs out properly.

-- I'm not mad at you, just Westphalian.