Electromagnetic scattering at high-frequencies is computationally heavy. Radar cross section (RCS) of electrically large concave and convex objects are solved by using the hybrid method. For convex and concave surfaces, Modified-Vector Physical Optics (MPO) with enhanced accuracy and Iterative Physical Optics (IPO) taking multiple-reflections into account, are selectively and independently applied for convex and concave parts of the scatterer. The accuracy of RCS by this hybrid method is tested with the MoM based simulator Wipl-D as the reference. The RCS from relatively small scatterers with the dimension of the order of a few wavelengths can be successfully predicted.