Direct imaging for extended targets Imaging function 1()=mam1a|2-1/(P2 OvI Where the normal direction at the boundaries is unknown we use a set of fixed search directions n,at eadhipolnt and take the maximum among them (過两科学大季 A Direct Numerical Imaging Method 15 National University of Defense TechnologyA Direct Numerical Imaging Method Direct imaging for extended targets 15 Imaging function where • the normal direction at the boundaries is unknown, we use a set of fixed search directions at each point and take the maximum among them. , 1,2, , l n l L = L