Positioning system registration using mechanical linkages

A positioning marker assembly comprising:

• one or more first markers having a geometric form configured to be detected using a first positioning modality;
• one or more second markers at least partially embedded within the geometric form of the one or more first markers and configured to be detected using a second modality, the one or more second markers including one or more conductive coils;
• and
• a physical linking structure securing the one or more first markers and the one or more second markers in a fixed relative position and orientation.

A positioning system comprising:

• a first emitter associated with a first positioning modality, wherein the first emitter is an electromagnetic field emitter;
• a second emitter associated with a second positioning modality that is of a different type than the first positioning modality;
• one or more first markers having a geometric form that is detectable using the second positioning modality:
• one or more second markers at least partially embedded within the geometric form of the one or more first markers and detectable using the first positioning modality;
• a C-arm configured to support the second emitter;
• and
• a rigid linking arm physically coupling the first emitter to a structure associated with the second emitter so that the first emitter is held away from the C-arm in a fixed, rigid relative position and orientation relative to the second emitter.