**4.1 Metric properties**

The metric properties for the algorithm are based on the Euclidean distance between two points in the image plane. The first step is to find the object in the image performing a pixellevel scan from top to bottom (first criterion) and left to right (second criterion). For instance, if an object in the image is higher than the others, this object will be considered first. In the event that all objects are from the same height, then the second criterion applies and the selected object will be the one located more to the left.
