A method for adding coloring information to a solid model of an actual object includes the steps of acquiring a solid model for forming a surface shape of the object from a set of multiple planes, and estimating coloring information at the plane, wherein the estimating step comprises the steps of regularly arranging multiple coloring points on the plane, and calculating coloring information of the coloring point as a constant in a predetermined function based on photo-image data photographed of the object illuminated by a light source and photography information of the photo-image data, and storing the calculated constants as a two-dimensional array corresponding to an arrangement of the coloring point.