Method and apparatus for robust optical tracking with beacon markers

A method for optical tracking in a video sequence comprising the steps of:

• placing at least one optical marker of a first kind (beacon kind), which can be quickly and robustly detected in an image, in a three-dimensional space to be viewed by a camera in a given pose for forming a camera image thereof;
• placing a plurality of optical markers of a second kind in said three-dimensional space in known predetermined relationships with said at least one optical marker of said first kind and with known predetermined 3D coordinates;
• locating an image of said optical marker of a first kind in said image and storing positional parameters thereof;
• utilizing said positional parameters and said known predetermined relationships to locate respective images of said plurality of optical markers of a second kind;
• storing respective location information for said images of said others of plurality of optical markers;
• and
• utilizing said 3D coordinates, said location information, and said respective location information for said images of said others of plurality of optical markers to derive said given pose of said camera.

A method for optical tracking in a video sequence comprising the steps of:

• placing optical markers in a 3-dimensional scene for viewing by a camera from a given camera pose, whereof certain preselected markers are designated optical beacons and being configured for ready location of images thereof in an image of said camera and others of said markers are placed in positions having known relative spatial relationship to said optical beacons and known 3D coordinates;
• finding images of said optical beacons in said image;
• finding images of a plurality of others of said optical markers by using existing knowledge of their relationship to said beacons;
• obtaining precise locations of optical markers;
• and
• using information of said precise locations of optical markers in said image in conjunction with known 3D coordinates of said markers and known internal parameters of said camera to obtain a precise camera pose.

A method for optical tracking in a video sequence comprising the steps of:

• placing optical markers in a 3-dimensional scene for viewing by a camera from a given camera pose, whereof certain preselected markers are designated optical beacons and being configured for ready location of images thereof in an image of said camera and others of said markers are placed in positions having known relative spatial relationship to said optical beacons and known 3-D coordinates;
• finding images of said optical beacons in said image;
• deriving from said image information on an approximate camera pose corresponding thereto;
• finding images of a plurality of others of said optical markers based on an estimate of their positions in said image derived from said approximate camera pose in conjunction with known 3D coordinates of said optical markers and known internal parameters of said camera;
• obtaining precise locations of optical markers;
• and
• using information of said precise locations of optical markers in said image in conjunction with known 3D coordinates of said markers and known internal parameters of said camera to obtain a precise camera pose.

Apparatus for optical tracking in a video sequence comprising:

• a camera;
• optical markers for placement in a 3-dimensional scene for viewing by said camera from a given camera pose, certain preselected markers being designated optical beacons and being configured for ready location of images thereof in an image of said camera and wherein others of said markers are placed in positions having known relative spatial relationship to said optical beacons, said beacons forming respective images in said image;
• and
• means for finding images of a plurality of others of said optical markers by using existing knowledge of their relationship to said beacons, for deriving from said image information on an approximate camera pose corresponding thereto, obtaining precise locations of optical markers, and for using information of said precise locations of optical markers to obtain a precise camera pose.

A method for finding and identifying optical markers in an image, said method comprising the steps of:

• placing a plurality of optical markers in a three-dimensional space;
• placing a plurality of optical beacon markers in the three-dimensional space which have particular spatial relationships with said optical markers;
• viewing said three dimensional space with a camera in a given pose for forming a camera image thereof;
• and
• finding and identifying the locations of the beacon markers in said camera image;
• and
• utilizing said knowledge of the beacon marker locations in conjunction with said spatial relationship to find and identify the locations of said optical markers in said image.