Image measuring and registering method

A method of measuring and registering positions and directions in an image space with positions and directions in a world space, the method comprising:

• a) providing an assembly and a tracking tool with six-degree freedom of positions and directions, wherein:
• the assembly includes objects including:
• either at least four noncoplanar positional objects, or at least one positional object and at least three orthogonal directional objects;
• the objects are rigidly placed in the assembly;
• the tracking tool is removably attached on the assembly rigidly, such that three-dimensional positions and available directions of the objects and positions and directions of the tracking tool are fixed relatively each other in the world space;
• the three-dimensional positions and the available directions of the objects in the world space are measured relative to a frame of the tracking tool;
• and
• the objects are configured to be scanned with imaging systems to obtain three-dimensional positions and available directions in the image space;
• b) placing the assembly on a body rigidly and taking imaging scanning with an imaging system to thereby obtain the three-dimensional positions and the available directions of the objects in the image space;
• c) computing a transformation of converting positions and directions from the world space into the image space, based on the three-dimensional positions and the available directions of the objects in the world space relative to the frame of the tracking tool measured in step a) and the three-dimensional positions and the available directions of the objects in the image space obtained in step b);
• d) placing a relative tracking tool with six-degree freedom of positions and directions on or in a target;
• with a tracking system, in a same time as a registering time, recording data of six-degree freedom of directions and positions for both the relative tracking tool and the tracking tool attached on the assembly with reference to the frame of the tracking system;
• e) placing an instrument tracking tool on an instrument to track pose of the instrument;
• with the tracking system, in a same time as a post-registering time, recording both data of positions and/or available directions of the instrument tracking tool attached on the instrument and data of six-degree freedom of positions and directions of the relative tracking tool with reference to the frame of the tracking system;
• f) combining the transformation obtained in step c), the data recorded during the registering time in step d) and the data recorded during the post-registering time in step e), to compute the positions and/or the available directions of the instrument tracking tool attached on the instrument in the image space.