Fine-Grained Alignment Supervision Matters in Vision-and-Language Navigation

The Vision-and-Language Navigation (VLN) task involves an agent navigating within 3D indoor environments based on provided instructions. Achieving cross-modal alignment presents one of the most critical challenges in VLN, as the predicted trajectory needs to precisely align with the given instruction. This paper focuses on addressing cross-modal alignment in VLN from a fine-grained perspective. Firstly, to address the issue of weak cross-modal alignment supervision arising from coarse-grained data, we introduce a human-annotated fine-grained VLN dataset called Landmark-RxR. This dataset aims to offer precise, fine-grained supervision for VLN. Secondly, in order to comprehensively demonstrate the potential and advantage of the fine-grained data from Landmark-RxR, we explore the core components of the training process that depend on the characteristics of the training data. These components include data augmentation, training paradigm, reward shaping, and navigation loss design. Leveraging our fine-grained data, we carefully design methods for handling them and introduce a novel evaluation mechanism. The experimental results demonstrate that the fine-grained data can effectively improve the agent's cross-modal alignment ability.