Finally, we obtain the total objective: where g i,l and d i,l denote the l-th column of G i and D i respectively, and ψ(t) is a piece-wise linear function defined as: This relaxation has a good intuitive explanation.
similar objects are desired to not only have the similar fingerprints but also have sufficient large projection magnitudes, while dissimilar objects are desired to not only differ in their fingerprints but also have large projection margin.