PLOP: Learning without Forgetting for Continual Semantic Segmentation

CVPR 2021  ยท  Arthur Douillard, Yifu Chen, Arnaud Dapogny, Matthieu Cord ยท

Deep learning approaches are nowadays ubiquitously used to tackle computer vision tasks such as semantic segmentation, requiring large datasets and substantial computational power. Continual learning for semantic segmentation (CSS) is an emerging trend that consists in updating an old model by sequentially adding new classes. However, continual learning methods are usually prone to catastrophic forgetting. This issue is further aggravated in CSS where, at each step, old classes from previous iterations are collapsed into the background. In this paper, we propose Local POD, a multi-scale pooling distillation scheme that preserves long- and short-range spatial relationships at feature level. Furthermore, we design an entropy-based pseudo-labelling of the background w.r.t. classes predicted by the old model to deal with background shift and avoid catastrophic forgetting of the old classes. Our approach, called PLOP, significantly outperforms state-of-the-art methods in existing CSS scenarios, as well as in newly proposed challenging benchmarks.

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Results from the Paper


Task Dataset Model Metric Name Metric Value Global Rank Result Benchmark
Overlapped 50-50 ADE20K MiB mIoU 29.31 # 6
Overlapped 50-50 ADE20K PLOP mIoU 30.4 # 3
Overlapped 100-5 ADE20K MiB mIoU 25.96 # 6
Overlapped 100-5 ADE20K PLOP mIoU 28.75 # 5
Overlapped 100-50 ADE20K MiB mIoU 32.79 # 6
Overlapped 100-50 ADE20K PLOP mIoU 32.94 # 5
Overlapped 100-10 ADE20K MiB Mean IoU (test) 29.24 # 5
Overlapped 100-10 ADE20K PLOP Mean IoU (test) 31.59 # 4
Domain 1-1 Cityscapes PLOP mIoU 45.2 # 2
Domain 11-1 Cityscapes PLOP mIoU 62.1 # 2
Domain 11-5 Cityscapes PLOP mIoU 63.5 # 2
Domain 11-5 Cityscapes val MiB Mean IoU 61.51 # 2
Domain 1-1 Cityscapes val PLOP Mean IoU 45.24 # 1
Domain 1-1 Cityscapes val MiB Mean IoU 42.15 # 2
Domain 11-1 Cityscapes val PLOP Mean IoU 62.05 # 1
Domain 11-1 Cityscapes val MiB Mean IoU 60.02 # 2
Domain 11-5 Cityscapes val PLOP Mean IoU 63.51 # 1
Overlapped 19-1 PASCAL VOC 2012 MiB Mean IoU (val) 69.15 # 4
Disjoint 15-5 PASCAL VOC 2012 PLOP Mean IoU 64.3 # 6
Overlapped 10-1 PASCAL VOC 2012 PLOP mIoU 30.45 # 8
Disjoint 10-1 PASCAL VOC 2012 PLOP mIoU 8.4 # 5
Disjoint 15-1 PASCAL VOC 2012 PLOP mIoU 46.5 # 5
Overlapped 15-1 PASCAL VOC 2012 MiB mIoU 29.29 # 10
Overlapped 15-1 PASCAL VOC 2012 PLOP mIoU 54.64 # 8
Overlapped 19-1 PASCAL VOC 2012 PLOP Mean IoU (val) 73.54 # 3
Overlapped 15-5 PASCAL VOC 2012 PLOP Mean IoU (val) 70.09 # 8
Overlapped 15-5 PASCAL VOC 2012 MiB Mean IoU (val) 70.08 # 9

Methods


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