Figure 7

Memory management in the pairwise stacks displacements computation step. The whole volume is processed a layer at the time, each composed by n _slices slices. For each layer, stacks are read row-wise when there are more rows than columns (i-iv). A new substack is loaded (i) when its North substack needs it for displacement computation (ii). After that, the North substack can be released (iii) and this process is repeated for the next column (iv).