Vision-Language Navigation in Continuous Environments (VLNCE), where an agent follows instructions and moves freely to reach a destination, is a key research problem in embodied AI. However, most existing approaches are sensitive to viewpoint changes, i.e. variations in camera height and viewing angle. Here we introduce a more general scenario, V²-VLNCE (VLNCE with Varied Viewpoints) and propose a view-invariant post-training framework, called VIL (View Invariant Learning), that makes existing navigation policies more robust to changes in camera viewpoint. VIL employs a contrastive learning framework to learn sparse and view-invariant features. We also introduce a teacher-student framework for the Waypoint Predictor Module, where a view-dependent teacher model distills knowledge into a view-invariant student model. Empirical results show that our method outperforms state-of-the-art approaches on V²-VLNCE by 8–15% measured on Success Rate for R2R-CE and RxR-CE. We further evaluate VIL on simulated robot camera placements and real-world robot navigation, showing consistent improvements in robustness.
The Varied Viewpoint challenge occurs when agents must generalize across environments with different egocentric camera placements, which is common in real-world robotics due to differences in sensor mounting. To systematically study this problem, we introduce V²-VLNCE (VLNCE with Varied Viewpoints), a generalized evaluation setting designed to measure navigation performance under diverse camera viewpoints.
We focus on two viewpoint variables: camera height and camera angle. For each navigation episode, a viewpoint is sampled from a two-dimensional distribution over height and angle ranges. This design better reflects realistic deployment conditions compared to fixed-viewpoint VLNCE settings.
Comparison between standard VLNCE and our proposed V²-VLNCE. Under viewpoint changes, baseline navigation policies suffer from degraded performance. Applying View Invariant Learning (VIL) improves robustness and enables stable navigation across varied viewpoints.
We propose View Invariant Learning (VIL), a strategy that adapts existing navigation policies to varied viewpoints without retraining from scratch. VIL contains two components: a contrastive learning objective and a teacher-student framework for waypoint prediction.
The contrastive component encourages sparse and view-invariant representations by aligning observations of the same scene captured from different viewpoints while separating unrelated observations. Features for contrastive learning are produced by a projection head and are shared with the navigation policy.
For waypoint prediction, a frozen teacher model, initialized from a pretrained navigation policy, processes observations from a standard viewpoint. The student model shares the same architecture but trains only a lightweight adapter inserted into the waypoint predictor while keeping the remaining parameters frozen. The student receives varied-viewpoint observations and learns to match the teacher outputs through a distillation loss.
Both components are optimized jointly in an end-to-end manner, enabling efficient adaptation to viewpoint variation while preserving the original navigation capability.
Comparison on R2R-CE and RxR-CE under the Varied Viewpoint and Ground-level Viewpoint settings. The Varied Viewpoint setting corresponds to our proposed V²-VLNCE setup. The Ground-level Viewpoint setting is adapted from GVNav. Evaluation metrics are consistent with GVNav. Bold indicates performance improvements introduced by VIL.
Performance under standard viewpoint (VLNCE).
Camera viewpoint (position) configuration: From the perspective of a Stretch RE-1 robot. View: Due to the geometric variations in camera height and pitch angle, all videos display the Front-View (egocentric RGB) to provide the most accurate representation of the agent's visual input.
Case 1 — ETPNav
Case 1 — VIL-ETPNav
Case 2 — ETPNav
Case 2 — VIL-ETPNav
Case 3 — ETPNav
Case 3 — VIL-ETPNav
Case 4 — BEVBert
Case 4 — VIL-BEVBert
Case 5 — BEVBert
Case 5 — VIL-BEVBert
Case 6 — BEVBert
Case 6 — VIL-BEVBert
@ARTICLE{11419772,
author={Sun, Josh Qixuan and Weng, Huaiyuan and Xing, Xiaoying and Yeum, Chul Min and Crowley, Mark},
journal={IEEE Robotics and Automation Letters},
title={View Invariant Learning for Vision-Language Navigation in Continuous Environments},
year={2026},
volume={11},
number={5},
pages={5861-5868},
doi={10.1109/LRA.2026.3669785}}