PT Journal AU Joakim Bruslund Haurum Meysam Madadi Sergio Escalera Thomas B. Moeslund TI Multi-scale hybrid vision transformer and Sinkhorn tokenizer for sewer defect classification SO Automation in Construction JI AC PY 2022 BP 104614 VL 144 DI 10.1016/j.autcon.2022.104614 DE Sewer Defect Classification; Vision Transformers; Sinkhorn-Knopp; Convolutional Neural Networks; Closed-Circuit Television; Sewer Inspection AB A crucial part of image classification consists of capturing non-local spatial semantics of image content. This paper describes the multi-scale hybrid vision transformer (MSHViT), an extension of the classical convolutional neural network (CNN) backbone, for multi-label sewer defect classification. To better model spatial semantics in the images, features are aggregated at different scales non-locally through the use of a lightweight vision transformer, and a smaller set of tokens was produced through a novel Sinkhorn clustering-based tokenizer using distinct cluster centers. The proposed MSHViT and Sinkhorn tokenizer were evaluated on the Sewer-ML multi-label sewer defect classification dataset, showing consistent performance improvements of up to 2.53 percentage points. ER