Disclosed embodiments include a method (system and non-transitory computer storage readable medium) for generating 3-dimensional model data of a virtual 3-dimensional model based on a plurality of 2-dimensional cross-sectional images of a 3-dimensional object. The 3-dimensional model of the 3-dimensional object is generated based on a plurality of virtual hexahedron models. The plurality of hexahedron models are generated based on respective pixels in the 2-dimensional cross-sectional images of the object. By generating the 3-dimensional model of the object including the plurality of hexahedron models, objects within another object can be accurately represented. In addition, the 3-dimensional model is guaranteed to have a closed shape, hence 3-dimensional printing of the 3-dimensional model can be performed successfully.