GROKE: Vision-Free Navigation Instruction Evaluation via Graph Reasoning on OpenStreetMap

Farzad Shami, Subhrasankha Dey, Nico Van de Weghe, Henrikki Tenkanen


Abstract
The evaluation of navigation instructions remains a persistent challenge in Vision-and-Language Navigation (VLN) research. Traditional reference-based metrics such as BLEU and ROUGE fail to capture the functional utility of spatial directives, specifically whether an instruction successfully guides a navigator to the intended destination. Although existing VLN agents could serve as evaluators, their reliance on high-fidelity visual simulators introduces licensing constraints and computational costs, and perception errors further confound linguistic quality assessment. This paper introduces GROKE (Graph-based Reasoning over OSM Knowledge for instruction Evaluation), a vision-free training-free hierarchical LLM-based framework for evaluating navigation instructions using OpenStreetMap data. Through systematic ablation studies, we demonstrate that structured JSON and textual formats for spatial information substantially outperform grid-based and visual graph representations. Our hierarchical architecture combines sub-instruction planning with topological graph navigation, reducing navigation error by 68.5% compared to heuristic and sampling baselines on the Map2Seq dataset. The agent’s execution success, trajectory fidelity, and decision patterns serve as proxy metrics for functional navigability given OSM-visible landmarks and topology, establishing a scalable and interpretable evaluation paradigm without visual dependencies.
Anthology ID:
2026.acl-long.1874
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
40371–40391
Language:
URL:
https://aclanthology.org/2026.acl-long.1874/
DOI:
10.18653/v1/2026.acl-long.1874
Bibkey:
Cite (ACL):
Farzad Shami, Subhrasankha Dey, Nico Van de Weghe, and Henrikki Tenkanen. 2026. GROKE: Vision-Free Navigation Instruction Evaluation via Graph Reasoning on OpenStreetMap. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 40371–40391, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
GROKE: Vision-Free Navigation Instruction Evaluation via Graph Reasoning on OpenStreetMap (Shami et al., ACL 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.acl-long.1874.pdf
Checklist:
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