1. A 3-dimensional (3D) model shape transformation method, comprising: generating a volume model, in which a shape of an object is restored, based on a plurality of 2D images of the object; generating a skeleton structure of the volume model using boundary points between portions of a body of the volume model; generating a skeleton transformation model by transforming a skeleton structure of a template model into the skeleton structure of the volume model in order to match a size and a posture of the template model with a size and a posture of the volume model; generating a shape transformation model corresponding to the shape of the object by transforming appearance of the skeleton transformation model based on cross-sections of the volume model in order to match appearance of the skeleton transformation model with appearance of the volume model; and generating the template model before generating the volume model, wherein the generating the template model comprises: generating a 3D skeleton model by forming a skeleton structure of a 3D mesh model; and generating the template model by transforming appearance of the 3D skeleton model based on each of relevant Non-Uniform Rational B-Spline (NURBS) surfaces, wherein the generating the template model by transforming the appearance of the 3D skeleton model comprises: extracting a cross-section of a predetermined location of the 3D skeleton model; and generating the NURBS surface by performing interpolation on the cross-section of a predetermined location of the 3D skeleton model, wherein the generating the shape transformation model comprises generating the shape transformation model by matching a cross-section of a predetermined location of the skeleton transformation model with a cross-section of the volume model.