  Semi-supervised semantic segmentation (SSS) has recently gained increasing
research interest as it can reduce the requirement for large-scale
fully-annotated training data. The current methods often suffer from the
confirmation bias from the pseudo-labelling process, which can be alleviated by
the co-training framework. The current co-training-based SSS methods rely on
hand-crafted perturbations to prevent the different sub-nets from collapsing
into each other, but these artificial perturbations cannot lead to the optimal
solution. In this work, we propose a new conflict-based cross-view consistency
(CCVC) method based on a two-branch co-training framework which aims at
enforcing the two sub-nets to learn informative features from irrelevant views.
In particular, we first propose a new cross-view consistency (CVC) strategy
that encourages the two sub-nets to learn distinct features from the same input
by introducing a feature discrepancy loss, while these distinct features are
expected to generate consistent prediction scores of the input. The CVC
strategy helps to prevent the two sub-nets from stepping into the collapse. In
addition, we further propose a conflict-based pseudo-labelling (CPL) method to
guarantee the model will learn more useful information from conflicting
predictions, which will lead to a stable training process. We validate our new
CCVC approach on the SSS benchmark datasets where our method achieves new
state-of-the-art performance. Our code is available at
https://github.com/xiaoyao3302/CCVC.
