A Modular Approach to Conversational Object Grounding in 3D Scenes Using VLMs and Prompt Chaining

Simon Keizer, Mohan Li, Youmna Farag, Svetlana Stoyanchev, Rama Doddipatla


Abstract
We introduce Conversational Object Grounding, a new task in which an agent must identify a target object in a complex 3D scene by engaging in natural language dialogue with a user who knows the target. It extends multimodal reference resolution on a single referring expression to conversations over multiple turns, combining it with clarification question generation and answer understanding to resolve ambiguities. For this task, we propose a zero-shot modular approach that combines the reference resolution, object captioning, and dialogue capabilities of foundation models, using prompt chaining in conjunction with an image-grounded scene graph. Evaluations on a new benchmark constructed with 3D scenes from ScanNet show that the proposed modular approach outperforms end-to-end baselines in terms of both grounding performance (up to 13% improvement) and image processing cost (up to 63% reduction).
Anthology ID:
2026.groundlm-1.74
Volume:
Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Yimu Wang, Yee Man Choi, Di Wu, Siqi Ouyang, Mozhgan Nasr Azadani, Yi R. (May) Fung
Venues:
GroundLM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1049–1074
Language:
URL:
https://aclanthology.org/2026.groundlm-1.74/
DOI:
Bibkey:
Cite (ACL):
Simon Keizer, Mohan Li, Youmna Farag, Svetlana Stoyanchev, and Rama Doddipatla. 2026. A Modular Approach to Conversational Object Grounding in 3D Scenes Using VLMs and Prompt Chaining. In Proceedings of the 1st Workshop on Grounding Language Models: Learning Faithfully and Efficiently (GroundLM 2026), pages 1049–1074, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
A Modular Approach to Conversational Object Grounding in 3D Scenes Using VLMs and Prompt Chaining (Keizer et al., GroundLM 2026)
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PDF:
https://aclanthology.org/2026.groundlm-1.74.pdf