Plan-and-Verify Video Reward Reasoning with Spatio-Temporal Scene Graph Grounding

Hyomin Kim, Junghye Kim, Joanie Hayoun Chung, Yoonjin Oh, Kyungjae Lee, Sungbin Lim, Sungwoong Kim


Abstract
Reward models for text-to-video (T2V) generation guide post-training but often fail at fine-grained semantic alignment. We trace this to two structural weaknesses in existing reasoning-based reward models: they do not systematically verify every condition described in the prompt, and the visual evidence supporting each judgment remains implicit in their free-form reasoning. We propose **SG-PVR**, a video reward model that addresses these limitations through plan-and-verify reasoning grounded in spatio-temporal scene graphs. The verification plan decomposes the prompt into atomic claims, making the set of requirements to be checked explicit. The spatio-temporal scene graph, encoding entities, attributes, and temporally grounded relations, is extracted from the video and maintained as a persistent structured visual reference throughout reasoning. Each claim is verified against both the video and the scene graph, anchoring judgments in explicit visual evidence. SG-PVR achieves strong performance on semantic alignment, including fine-grained temporal semantics. As a test-time reranker, it further enhances compositional alignment in T2V generation.
Anthology ID:
2026.emnlp-main.2257
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
51317–51350
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2257/
DOI:
Bibkey:
Cite (ACL):
Hyomin Kim, Junghye Kim, Joanie Hayoun Chung, Yoonjin Oh, Kyungjae Lee, Sungbin Lim, and Sungwoong Kim. 2026. Plan-and-Verify Video Reward Reasoning with Spatio-Temporal Scene Graph Grounding. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 51317–51350, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Plan-and-Verify Video Reward Reasoning with Spatio-Temporal Scene Graph Grounding (Kim et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2257.pdf