Method for registering three-dimensional representations of an object on the object itself and device for providing navigation assistance in an object implementing said method

A device for navigation assistance in an object, comprising:

• a memory for storing a first three-dimensional representation of the object according to a first three-dimensional imaging mode, locations of at least three reference points of the object in said first three-dimensional representation, a second three-dimensional representation of the object according to a second three-dimensional imaging mode other than the first three-dimensional imaging mode, and locations of the reference points of the object in said second three-dimensional representation;
• a computing unit designed for three-dimensional registration of said first and second three-dimensional representations of the object on the object itself;
• a referencing ancillary for attachment to the object;
• a stylus, a tip of which can be located in a three-dimensional reference frame linked to the referencing ancillary;
• an instrument, a functional end of which can be located in the three-dimensional reference frame linked to the referencing ancillary;
• and
• a screen for simultaneous display of several planar cross-sectional reconstructions of the object, including at least two planar reconstructions of the same cross-section of the object obtained respectively from one and the other of the first and second three-dimensional representations;
• wherein the computing unit is more precisely designed to perform:
• a three-dimensional angular registration of the first three-dimensional representation on the object based on a recording, by interaction with the tip of the stylus when manipulated by an operator, of the locations of the object's reference points in the three-dimensional reference frame linked to the referencing ancillary;
• a three-dimensional surface registration of the first three-dimensional representation on the object, comprising:
• extracting a surface of the object in the first three-dimensional representation,
• recording the locations of a plurality of surface points other than the reference points on the surface of the object in the three-dimensional reference frame linked to the referencing ancillary, and
• computing the three-dimensional surface registration from this said surface point location recording;
• the computing unit being designed so that the three-dimensional registration of the second three-dimensional representation comprises a three-dimensional surface registration of said second three-dimensional representation on the basis of the registration of locations of surface points carried out for the surface registration of the first three-dimensional representation;
• wherein the recording of the locations of the plurality of surface points other than the reference points on the surface of the object in the three-dimensional reference frame linked to the referencing ancillary takes place by interaction using the tip of the stylus when it is manipulated by an operator;
• and
• wherein the computing unit is designed to switch the display between a plurality of planar cross-sectional reconstructions of the object according to the first three-dimensional representation, a plurality of planar cross-sectional reconstructions of the object according to the second three-dimensional representation and a plurality of planar cross-sectional reconstructions of the object according to the first and second three-dimensional representations, said switching being activated by a predetermined approach between the functional end of the instrument and a calibration pin of the referencing ancillary.