Methods and devices for tracking objects by surgical navigation systems

A method of tracking an object in a surgical coordinate space by a surgical navigation system including an optical imaging device, the tracked object having a reference body affixed thereto, the reference body comprising a substrate and a first layer affixed to the substrate, the first layer including a plurality of totem patterns, each totem pattern having a unique identifiable feature distinguishing that totem pattern from another totem pattern in the plurality of totem patterns, the method comprising:

• capturing an image of the tracked object, the image including image data associated with at least one totem pattern;
• determining whether a unique identifiable feature associated with at least one totem pattern is discernible in the image;
• when the unique identifiable feature associated with at least one totem pattern is discernible:
• determining a position or an orientation of the tracked object in the surgical coordinate space based on the at least one totem pattern;
• and
• registering the at least one totem pattern associated with the tracked object in the surgical coordinate space;
• and
• when the unique identifiable feature associated with at least one totem pattern is indiscernible:
• determining a position of each totem pattern relative to other totem patterns in the captured image such that a combination of totem patterns within the captured image is a marker group detectable by the surgical navigation system as a composite totem pattern;
• determining a position or an orientation of the tracked object in the surgical coordinate space based on the composite totem pattern associated with the tracked object;
• and
• registering the composite totem pattern associated with the tracked object in the surgical coordinate space.