Fig. 2.

Mean squared error of the exit wave of a subregion of a 3D object as a function of the buffer zone width $r_2=(w/\sqrt{2})\sqrt{\lambda z_{\text{prop}}}$ of Eq. (13), showing that the choice of $r_2=3.97\sqrt{\lambda z}$ of Eq. (14) gives good results (a mean squared error of ${10}^{-9}$ compared to a variance in the reference modulus of $4\times {10}^{-6}$). Shown here is the result of using tiling-based short-distance propagation through a ${256}^3$ voxel object as used in another publication [12]. The object was split into 4 $128\times 128$ tiles with the “seams” of the tiles running across the object, and buffer zones are added around each tile.