TDMPNet: Prototype Network with Recurrent Top-Down Modulation for Robust Object Classification under Partial Occlusion
Keywords: object recognition, occlusion, prototype, feature dictionary, top-down modulation
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TL;DR: Introduce partial prototype matching and top-down modulation into deep neural networks for robust object classification under occlusion that do not appear in the training data.
Abstract: Despite deep convolutional neural networks' great success in object classification, recent work has shown that they suffer from a severe generalization performance drop under occlusion conditions that do not appear in the training data. Due to the large variability of occluders in terms of shape and appearance, training data can hardly cover all possible occlusion conditions. However, in practice we expect models to reliably generalize to various novel occlusion conditions, rather than being limited to the training conditions. In this work, we integrate inductive priors including prototypes, partial matching and top-down modulation into deep neural networks to realize robust object classification under novel occlusion conditions, with limited occlusion in training data. We first introduce prototype learning as its regularization encourages compact data clusters for better generalization ability. Then, a visibility map at the intermediate layer based on feature dictionary and activation scale is estimated for partial matching, whose prior sifts irrelevant information out when comparing features with prototypes. Further, inspired by the important role of feedback connection in neuroscience for object recognition under occlusion, a structural prior, i.e. top-down modulation, is introduced into convolution layers, purposefully reducing the contamination by occlusion during feature extraction. Experiment results on partially occluded MNIST, vehicles from the PASCAL3D+ dataset, and vehicles from the cropped COCO dataset demonstrate the improvement under both simulated and real-world novel occlusion conditions, as well as under the transfer of datasets.