As far as I understood it, Max Pooling takes the maximum positive value and not absolute values.

In this paper, optimized mechanical structures get generated with a U-Net by feeding it mechanical information like nodal displacement, element strains, and volume fractions.

https://arxiv.org/ftp/arxiv/papers/1901/1901.07761.pdf

My question now is: won’t Max Pooling mess up a lot of information, if it just takes the positive value and not the absolute value? Since positive elements in the strain matrix correspond to tensile strains and negative to compressive ones.