Configuration marker design and detection for instrument tracking

A medical system, comprising:

• a tool having a distal end that is insertable into a patient body, wherein the distal end has three primitive features having known positions on the tool, wherein each primitive feature comprises a spherical reflective surface, wherein the three primitive features include a natural feature of the tool and an artificial feature of the tool, wherein the natural feature includes one of an end of a bolt and an end of a hinge of the tool and is a component of the tool that is provided for either construction or operation of the tool, and wherein the artificial feature is included on the tool to a spherical reflective surface;
• a light source insertable into the patient body so as to be oriented to direct light toward the distal end of the tool when the distal end is within the patient body;
• a stereo image capture device insertable into the patient body so that the stereo image capture device captures stereo images of bright spots generated by the light source directing light on the three primitive features, the bright spots substantially aligned with spherical centers of the spherical surfaces;
• and
• a processor coupled to the image capture device and configured to determine a pose of the tool by processing the stereo images so as to locate the spherical centers by using the bright spots and based on an estimated pose of the tool generated by using at least one prior pose of the tool from stereo image data of the tool for a prior time or joint data from a robotic actuation system effecting movement of the tool.