  Open Set Domain Adaptation (OSDA) bridges the domain gap between a labeled
source domain and an unlabeled target domain, while also rejecting target
classes that are not present in the source. To avoid negative transfer, OSDA
can be tackled by first separating the known/unknown target samples and then
aligning known target samples with the source data. We propose a novel method
to addresses both these problems using the self-supervised task of rotation
recognition. Moreover, we assess the performance with a new open set metric
that properly balances the contribution of recognizing the known classes and
rejecting the unknown samples. Comparative experiments with existing OSDA
methods on the standard Office-31 and Office-Home benchmarks show that: (i) our
method outperforms its competitors, (ii) reproducibility for this field is a
crucial issue to tackle, (iii) our metric provides a reliable tool to allow
fair open set evaluation.
