Online vs Offline Triplet Selection in FaceNet I have been reading FaceNet. In the Triplet Selection section, it is written

Generate triplets offline every n steps, using the most
recent network checkpoint and computing the argmin
and argmax on a subset of the data.

and

Generate triplets online. This can be done by selecting the hard positive/negative exemplars from within a mini-batch.

The words "online" and "offline" make me puzzled. What do "online" and "offline" mean in this context?

I think it's too late but anyway.
Offline means you make your triplet first, and then make mini batches from those triplets while online means you make triplets after a mini batch of samples, and so in each mini batch training you have to go through the triplet selection for that mini batch.
Here is a good explanation provided by the following link.
Triplet Loss
