Cut-view images for the yz, xz, and xy planes (left, middle, and right, respectively) of the target. Reconstruction layers 1 (red) and 2 (grey) are visualised for each reconstruction case ((I)–(V)) and all four measurement configurations. The exact structures of the mantle and the void are depicted by the green and black areas, respectively. Optimally, layers 1 and 2 exactly match these areas.