# Hausdorff Distance Computes the Hausdorff distance and average Hausdorff distance between the set of non-zero pixels of two images. The Hausdorff distance measures the degree of mismatch between two sets. The average Hausdorff distance is the Hausdorff distance averaged over all points in the two masks. To get the Hausdorff distance (HD), one first calculates the shortest distance from every point in one set to the other set, and find the maximum of all the shortest distances. This is called the one-sided HD (hd). This is done for both sets. The Hausdorff distance is the maximum of the one-sided HDs of the two sets. In essence, the HD is the is the longest distance one has to travel from a point in one of the two sets to its closest point in the other set. This measure is a good indication of the difference between two sets, such as e.g. a segmentation mismatch.

If more than two images are supplied to the node, the Hausdorff distance will be calculated between all combinations of input masks.