You will need the TSCC codec
Look the difference beteween TSCC and Microsoft Codec in this video:
http://youtu.be/5Vqc-jMpvfU
http://youtu.be/6q3SLGhlPGg
You need a rhino3d for this. http://www.rhino3d.com/
export file as STP from nx, and open in rhino3d and export like a 3ds file.
stay perfect.
iges is not good for this.