IMAGE MEASURING AND REGISTERING METHOD

Methods for measuring and registering positions and directions in image space with that in world space includes: providing an assembly with a tracking tool; the assembly including positional and/or directional objects with positions and available directions measured according to the tracking tool's frame with a measuring piece having a measuring surface for measuring without prior calibration with a measuring tracking tool in a tracking system; placing the assembly on a body and perform scanning; placing a relative tracking tool at the body; in registering time, recording the data for both the relative tracking tool and the tracking tool attached to the assembly; placing a tracking tool on an instrument; in post-registering time, recording both data of the tracking tool attached on the instrument and data of the relative tracking tool; computing converted positions and/or available directions of the tracking tool attached on the instrument in the image space.