Think Global, Act Local: Dual-scale Graph Transformer for Vision-and-Language Navigation

Shizhe Chen1
Pierre-Louis Guhur1
Makarand Tapaswi2
Cordelia Schmid1
Ivan Laptev1
1 Inria, École normale supérieure, CNRS, PSL Research University    2 IIIT Hyderabad


Following language instructions to navigate in unseen environments is a challenging problem for autonomous embodied agents. The agent not only needs to ground languages in visual scenes, but also should explore the environment to reach its target. In this work, we propose a dual-scale graph transformer (DUET) for joint long-term action planning and fine-grained cross-modal understanding. We build a topological map on-the-fly to enable efficient exploration in global action space. To balance the complexity of large action space reasoning and fine-grained language grounding, we dynamically combine a fine-scale encoding over local observations and a coarse-scale encoding on a global map via graph transformers. The proposed approach, DUET, significantly outperforms state-of-the-art methods on goal-oriented vision-and-language navigation (VLN) benchmarks REVERIE and SOON. It also improves the success rate on the fine-grained VLN benchmark R2R.


DUET consists of topological mapping (left) and global action planning (right). The mapping module outputs a graph with K node features {v1, ..., vK}, and the current panorama encoding with image features {r1, ..., rn} and object features {o1, ..., om}. Node feature v0 and image feature r0 are used to indicate the 'stop' action. The global action planning uses transformers for coarse- and fine-scale cross-modal encoding and fuses the two scales to obtain a global action score si for each node.

Video: Result Visualization



    author    = {Chen, Shizhe and Guhur, Pierre-Louis and Tapaswi, Makarand and Schmid, Cordelia and Laptev, Ivan},
    title     = {Think Global, Act Local: Dual-scale Graph Transformer for Vision-and-Language Navigation},
    booktitle = {CVPR},
    year      = {2022}


This work was granted access to the HPC resources of IDRIS under the allocation 101002 made by GENCI. It was funded in part by the French government under management of Agence Nationale de la Recherche as part of the “Investissements d’avenir” program, reference ANR19-P3IA-0001 (PRAIRIE 3IA Institute) and by Louis Vuitton ENS Chair on Artificial Intelligence.