Position and orientation measurement apparatus and method thereof

A position and orientation measurement method comprising:

• inputting an image captured by an imaging apparatus;
• reading out three-dimensional model data which represents a surface shape of an observation object from a memory;
• extracting a plurality of geometric feature based on geometric information about the observation object by drawing the three-dimensional model data;
• storing a at least one reference image in which a position and orientation of the imaging apparatus relative to the observation object is known;
• selecting from the plurality of geometric features a geometric feature that corresponds to an image feature in the reference image;
• and
• calculating the position and orientation of the imaging apparatus relative to the observation object by associating the selected geometric feature with an image of the observation object in the input image.

A position and orientation measurement apparatus comprising:

• an input unit configured to input an image captured by an imaging apparatus;
• a storage unit configured to store three-dimensional model data which represents a surface shape of an observation object;
• a geometric feature extraction unit configured to extract a plurality of geometric features using the three-dimensional model data;
• a reference image storage unit configured to store at least one reference image in which a position and orientation of the imaging apparatus relative to the observation object is known;
• a determination unit configured to determine the geometric features to be associated, based on the plurality of geometric features extracted by the geometric feature extraction unit and the reference image;
• and
• a calculation unit configured to calculate the position and orientation of the imaging apparatus relative to the observation object by associating the geometric feature determined by the determination unit with an image of the observation object in the image input by the input unit.