System for measuring true dimensions and orientation of objects in two dimensional image

The surgical navigation system comprises: a surgical tool designed to perform a surgical process and including a set of markers visible in medical images and having known spatial relationships between them; a receiving circuitry adapted to receive a given medical image, which given medical image includes the surgical tool and an organ of a subject; and an image processing circuitry adapted to identify said markers in the given medical image, to determine a location and orientation of the surgical tool based on the location of the identified markers in the image; and to generate and render an overlay on the image derived from the determined location and orientation.