“…Most existing methods take two typical approaches, namely, adversarial learning based [24,59,62,60,40,26,50,21] 35,36,65,32,67,44]. The adversarial learning based methods perform domain alignment by adopting a discriminator that strives to differentiate the segmentation in the space of inputs [24,66,35,12,32], features [61,24,11,66,40] or outputs [59,62,41,60,26,42,63,50,21]. The self-training based methods exploit self-training to predict pseudo labels for target-domain data and then exploit the predicted pseudo labels to fine-tune the segmentation model iteratively.…”