In the example structure Identify Pores finds four individual pores, which might be the same that a human eye would identify. The boundary conditions were set to be periodic in Y-direction, thus, the pore at the right side of the structure enters again on the left side.

When using Identify Pores, first a Euclidean distance transformation and then a Watershed transformation are performed. The minima of the negative distance transform define the seeds for the following watershed transformation (in the example in the middle of the three red zones and the green voxel of the closed pore). Here, as seen in the next figure, starting from the seeds, the algorithm proceeds to higher and higher values of the distance transform, and labels those voxels with the index of the seed they are connected with. This is done until all voxels have been reached.

If two voxel of different seeds touch during this process, they mark the boundary between two neighboring pores. If selected, fragmented pores can be reconnected, i.e., a smaller pore is associated to a bigger neighbor. After the Watershed transformation is done, an ellipsoid is fitted into each of the identified pores. In the report, the orientation of the three axes, the length of the three axes, and more parameters are given to describe the pore sizes. See Results of Identify Pores for a description of all computed parameters.