  This paper proposes a method for detecting multiple scatterers (targets) in
the elevation direction for synthetic aperture radar (SAR) tomography. The
proposed method can resolve closely spaced targets through a twostep procedure.
In the first step, coarse detection is performed with a successive cancellation
scheme in which possible locations of targets are marked. Then, in the second
step, by searching in the reduced search space which is finely 10 gridded, the
accurate location of the targets is found. For estimating the actual number of
targets, a model order selection scheme is used in two cases of known and
unknown noise variance. Also, by analytical investigation of the probability of
detection for the proposed method, the effect of the influential parameters on
the detection ability is explicitly demonstrated. Compared to the
super-resolution methods based on compressed sensing (CS), the proposed method
has a lower computational cost and higher estimation accuracy, especially at
low signal-to-noise ratio regime. 15 Simulation results show the superiority of
the proposed method in terms of both 3D scatterer reconstruction and detection
ability
