Dynamic visual registration of a 3-D object with a graphical model

Claim 1

A method for finding the relative position and orientation of an imaging device in relation to an imaged object, wherein said imaging device produces a video signal representing a two-dimensional projection of said imaged object onto an image frame, the method comprising the steps of: recognizing a plurality of features from the video signal; associating with each recognized feature a two-dimensional position in the image frame; computing a disparity between the positions of the features and corresponding positions of features in a calculated projection of a stored, three-dimensional object model, said calculated projection calculated according to a virtual camera model; and varying parameters of the virtual camera model, consistent with a projective geometric model, to reduce said disparity; wherein said disparity is reduced by computing and applying a transformation matrix including translation sub-matrix and rotation sub-matrix, and wherein said sub-matrices are calculated from translation and rotation sub-vectors of a vector obtained by multiplying a constant with a product of an error function and a pseudo-inverse of an interaction matrix L; wherein said interaction matrix L represents two dimensional coordinates xp, yp and a depth Z for a plurality of pre-defined points in a calculated three dimensional object model, and said two dimensional coordinates xp, yp are calculated projected positions of said pre-defined points onto a hypothetical plane of projection which corresponds to an image plane of said virtual camera model.

Claim 2

A method for finding the relative position and orientation of an imaging device in relation to an imaged object, wherein said imaging device produces a video signal representing a two-dimensional projection of said imaged object onto an image frame, the method comprising the steps of: recognizing a plurality of features from the video signal; associating with each recognized feature a two-dimensional position in the image frame; computing a disparity between the positions of the features and corresponding positions of features in a calculated projection of a stored, three-dimensional object model, said calculated projection calculated according to a virtual camera model; and varying parameters of the virtual camera model, consistent with a projective geometric model, to reduce said disparity; wherein said disparity is reduced by computing and applying a transformation matrix including translation sub-matrix and rotation sub-matrix, and wherein said sub-matrices are calculated from translation and rotation sub-vectors of a vector obtained by multiplying a constant with a product of an error function and a pseudo-inverse of an interaction matrix L; wherein said interaction matrix L represents two dimensional coordinates xp, yp and a depth Z for a plurality of pre-defined points in a calculated three dimensional object model, and said two dimensional coordinates xp, yp are calculated projected positions of said pre-defined points onto a hypothetical plane of projection which corresponds to an image plane of said virtual camera model.

Claim 6

A method of registering a two-dimensional object image of a three-dimensional object with a stored, three-dimensional model having a predetermined spatial relationship to the three-dimensional object, comprising the steps of: identifying the positions of a plurality of features in said object image; rendering a virtual image by projecting at least portions of said three-dimensional model onto a virtual image plane; calculating an error function which measures a difference between positions of said plurality of features in said object image and corresponding positions of previously associated features in said virtual image; finding a position and/or orientation of said virtual image plane which reduces said error function, wherein said position and/or orientation are found by computing and applying a transformation matrix including a translation sub-matrix and a rotation sub-matrix, and wherein said sub-matrices are calculated from translation and rotation sub-vectors of a vector obtained by multiplying a constant with a product of an error function and a pseudo-inverse of an interaction matrix L; wherein said interaction matrix L represents two dimensional coordinates xp, yp and a depth Z for a plurality of pre-defined points in a calculated three dimensional object model, and said two dimensional coordinates xp, yp are calculated projected positions of said pre-defined points onto the virtual image plane.

Claim 7

A method of registering a two-dimensional object image of a three-dimensional object with a stored, three-dimensional model having a predetermined spatial relationship to the three-dimensional object, comprising the steps of: identifying the positions of a plurality of features in said object image; rendering a virtual image by projecting at least portions of said three-dimensional model onto a virtual image plane; calculating an error function which measures a difference between positions of said plurality of features in said object image and corresponding positions of previously associated features in said virtual image; finding a position and/or orientation of said virtual image plane which reduces said error function, wherein said position and/or orientation are found by computing and applying a transformation matrix including a translation sub-matrix and a rotation sub-matrix, and wherein said sub-matrices are calculated from translation and rotation sub-vectors of a vector obtained by multiplying a constant with a product of an error function and a pseudo-inverse of an interaction matrix L; wherein said interaction matrix L represents two dimensional coordinates xp, yp and a depth Z for a plurality of pre-defined points in a calculated three dimensional object model, and said two dimensional coordinates xp, yp are calculated projected positions of said pre-defined points onto the virtual image plane.