A position and orientation determination apparatus for identifying a parameter
indicating the position and orientation of image sensing apparatus which performs
image sensing on actual space where plural feature points exist in already-known
positions. In the position and orientation determination apparatus, the position
and orientation of the image sensing apparatus can be measured by a method other
than utilization of video image obtained by image sensing, and a parameter indicating
the position and orientation of the image sensing apparatus is obtained. Then,
the parameter is corrected based on the plural feature points in the video image
of actual space obtained by image sensing by the image sensing apparatus, and a
parameter indicating the position and orientation of the image sensing apparatus
is identified. Upon correction of the parameter, first, the parameter is corrected
by a general method using the feature points, and then correction is performed
by rotation about a visual axis, thereby the position and orientation of the image
sensing apparatus can be detected with high accuracy.