1. A method for creating a 3-Dimensional model for objects in an inspected luggage in a CT system, comprising: acquiring slice data of the luggage with the CT system; interpolating the slice data to generate 3D volume data of the luggage; performing unsupervised segmentation on the 3D volume data of the luggage to obtain a plurality of segmental regions; performing isosurface extraction on the plurality of segmental regions to obtain corresponding isosurfaces; and performing 3D surface segmentation on the isosurfaces to form a 3D model for the objects in the luggage.