TransVLAD: multi-scale attention-based global descriptors for visual geo-localization

Visual geo-localization remains a challenging task due to variations in the appearance and perspective among captured images. This paper introduces an efficient TransVLAD module, which aggregates attention-based feature maps into a discriminative and compact global descriptor. Unlike existing methods that generate feature maps using only convolutional neural networks (CNNs), we propose a sparse transformer to encode global dependencies and compute attention-based feature maps, which effectively reduces visual ambiguities that occurs in large-scale geo-localization problems. A positional embedding mechanism is used to learn the corresponding geometric configurations between query and gallery images. A grouped VLAD layer is also introduced to reduce the number of parameters, and thus construct an efficient module. Finally, rather than only learning from the global descriptors on entire images, we propose a self-supervised learning method to further encode more information from multi-scale patches between the query and positive gallery images. Extensive experiments on three challenging large-scale datasets indicate that our model outperforms state-of-the-art models, and has lower computational complexity. The code is available at: https://github.com/wacv-23/TVLAD.