A Multimodal Tensor-Based Late Fusion Approach for Satellite Image Search in Sentinel 2 Images

Abstract

Earth Observation (EO) Big Data Collections are acquired at large volumes and variety, due to their high heterogeneous nature. The multimodal character of EO Big Data requires effective combination of multiple modalities for similarity search. We propose a late fusion mechanism of multiple rankings to combine the results from several uni-modal searches in Sentinel 2 image collections. We fist create a K-order tensor from the results of separate searches by visual features, concepts, spatial and temporal information. Visual concepts and features are based on a vector representation from Deep Convolutional Neural Networks. 2D-surfaces of the K-order tensor initially provide candidate retrieved results per ranking position and are merged to obtain the final list of retrieved results. Satellite image patches are used as queries in order to retrieve the most relevant image patches in Sentinel 2 images. Quantitative and qualitative results show that the proposed method outperforms search by a single modality and other late fusion methods.