An apparatus reconstructs a three dimensional shape of an object from a plurality of images captured from different viewpoints by visual hull. The apparatus stores, into a first memory provided for the apparatus, silhouette image data of the object extracted from the plurality of images, and determines a group of a plurality of epipolar lines having inclinations within a predetermined range in images designated as reference views among the plurality of images, based on positions of neighboring silhouette pixels in an image designated as a target view among the plurality of images. The apparatus further determines, based on the determined group and a capacity of a cache provided for the apparatus, a cache area to be used in a search for a line segment indicating a range where the object exists in each of the plurality of epipolar lines in the group.