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UBC Theses and Dissertations

Graph-based language grounding Bajaj, Mohit


In recent years, phrase (or more generally language) grounding has emerged as a fundamental task in computer vision. Phrase grounding is a generalization of more traditional computer vision tasks with the goal of localizing a natural language phrase spatially in a given image. Most recent work use state-of-the-art deep learning techniques to achieve good performance on this task. However, they do not capture complex dependencies among proposal regions and phrases that are crucial for the superior performance on the task. In this work we try to overcome this limitation through a model that makes no assumptions regarding the underlying dependencies in both of the modalities. We present an end-to-end framework for grounding of the phrases in images that uses graphs to formulate more complex, non-sequential dependencies among proposal image regions and phrases. We capture intra-modal dependencies using a separate graph neural network for each modality (visual and lingual), and then use conditional message-passing in another graph neural network to fuse their outputs and capture cross-modal relationships. This final representation is used to make the grounding decisions. The framework supports many-to-many matching and is able to ground single phrase to multiple image regions and vice versa. We validate our design choices through a series of ablation studies and demonstrate state-of-the-art performance on the Flickr30k Entities dataset and the ReferIt Game dataset.

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Attribution-NonCommercial-NoDerivatives 4.0 International