A method includes associating a plurality of first feature points with a plurality of second feature points, the plurality of first feature points being included in a keyframe that represents a first captured image at a first time when a position and an orientation of a camera are successfully estimated, the plurality of second feature points being included in a second captured image captured at a second time, calculating vectors based on feature descriptors of the first feature points and feature descriptors of the second feature points for respective pairs of the first feature points and the second feature points, determining whether an association of the first feature points and the second feature points is satisfactory, and performing an estimation process that estimates a new position and a new orientation of the camera at the second time when the association is determined to be satisfactory.