Actually, loss of smoothing information is one of the main reasons I am working on a b3d exporter for Maya. I convert via Ultimate Unwrap and I don't know of any way to preserve smoothing information. You can separate hard-edged regions in Ultimate Unwrap and exporting to b3d from Ultimate Unwrap preserves smoothing information perfectly, but I don't know how to get from Maya to Ultimate Unwrap with smoothing intact.
It is entirely possible however that I just haven't tried the right thing (possibly something pretty obvious) to get the smoothing into Ultimate Unwrap and, as I said, Ultimate Unwrap does export smoothing information perfectly. In fact, I'll try a couple things I just thought of right now and report here if they work.
It is entirely possible however that I just haven't tried the right thing (possibly something pretty obvious) to get the smoothing into Ultimate Unwrap and, as I said, Ultimate Unwrap does export smoothing information perfectly. In fact, I'll try a couple things I just thought of right now and report here if they work.