1,025 research outputs found
RGB2LIDAR: Towards Solving Large-Scale Cross-Modal Visual Localization
We study an important, yet largely unexplored problem of large-scale
cross-modal visual localization by matching ground RGB images to a
geo-referenced aerial LIDAR 3D point cloud (rendered as depth images). Prior
works were demonstrated on small datasets and did not lend themselves to
scaling up for large-scale applications. To enable large-scale evaluation, we
introduce a new dataset containing over 550K pairs (covering 143 km^2 area) of
RGB and aerial LIDAR depth images. We propose a novel joint embedding based
method that effectively combines the appearance and semantic cues from both
modalities to handle drastic cross-modal variations. Experiments on the
proposed dataset show that our model achieves a strong result of a median rank
of 5 in matching across a large test set of 50K location pairs collected from a
14km^2 area. This represents a significant advancement over prior works in
performance and scale. We conclude with qualitative results to highlight the
challenging nature of this task and the benefits of the proposed model. Our
work provides a foundation for further research in cross-modal visual
localization.Comment: ACM Multimedia 202
Multiple Visual-Semantic Embedding for Video Retrieval from Query Sentence
Visual-semantic embedding aims to learn a joint embedding space where related
video and sentence instances are located close to each other. Most existing
methods put instances in a single embedding space. However, they struggle to
embed instances due to the difficulty of matching visual dynamics in videos to
textual features in sentences. A single space is not enough to accommodate
various videos and sentences. In this paper, we propose a novel framework that
maps instances into multiple individual embedding spaces so that we can capture
multiple relationships between instances, leading to compelling video
retrieval. We propose to produce a final similarity between instances by fusing
similarities measured in each embedding space using a weighted sum strategy. We
determine the weights according to a sentence. Therefore, we can flexibly
emphasize an embedding space. We conducted sentence-to-video retrieval
experiments on a benchmark dataset. The proposed method achieved superior
performance, and the results are competitive to state-of-the-art methods. These
experimental results demonstrated the effectiveness of the proposed multiple
embedding approach compared to existing methods.Comment: 8 pages, 5 figure
Sign language video retrieval with free-form textual queries
Systems that can efficiently search collections of sign language videos have been highlighted as a useful application of sign language technology. However, the problem of searching videos beyond individual keywords has received limited attention in the literature. To address this gap, in this work we introduce the task of sign language retrieval with textual queries: given a written query (e.g. a sentence) and a large collection of sign language videos, the objective is to find the signing video that best matches the written query. We propose to tackle this task by learning cross-modal embeddings on the recently introduced large-scale How2Sign dataset of American Sign Language (ASL). We identify that a key bottleneck in the performance of the system is the quality of the sign video embedding which suffers from a scarcity of labelled training data. We, therefore, propose SPOT-ALIGN, a framework for interleaving iterative rounds of sign spotting and feature alignment to expand the scope and scale of available training data. We validate the effectiveness of SPOT-ALIGN for learning a robust sign video embedding through improvements in both sign recognition and the proposed video retrieval task.This work was supported by the project PID2020-117142GB-I00, funded by MCIN/ AEI /10.13039/501100011033, ANR project CorVis ANR-21-CE23-0003- 01, and gifts from Google and Adobe. AD received support from la Caixa Foundation (ID 100010434), fellowship code LCF/BQ/IN18/11660029.Peer ReviewedObjectius de Desenvolupament Sostenible::10 - Reducció de les DesigualtatsObjectius de Desenvolupament Sostenible::10 - Reducció de les Desigualtats::10.2 - Per a 2030, potenciar i promoure la inclusió social, econòmica i política de totes les persones, independentment de l’edat, sexe, discapacitat, raça, ètnia, origen, religió, situació econòmica o altra condicióPostprint (author's final draft
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