Semantic Radiance Fields as Simulators for Spatial Reasoning in Real-World Scenes

Nico Heider; Michał Jan Włodarczyk; Katarzyna Wasielewska-Michniewska; Przemysław Hołda; Martin Schieck; Marcin Paprzycki; Maria Ganzha; Bogdan Franczyk

arXiv · 2608.13095

Semantic Radiance Fields as Simulators for Spatial Reasoning in Real-World Scenes

Nico Heider·Michał Jan Włodarczyk·Katarzyna Wasielewska-Michniewska·Przemysław Hołda·Martin Schieck·Marcin Paprzycki·Maria Ganzha·Bogdan Franczyk

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Abstract

Training and evaluating spatial reasoning in embodied agents requires diverse environments that are both geometrically faithful and semantically queryable. Synthetic simulators offer ground truth semantics but sacrifice realism; simulators based on reconstructions of real-world environments have realistic appearance but lack ground truth semantics by default. We propose using Semantic Radiance Fields (SRF) as simulators for spatial reasoning agents. SRFs are a representation that unifies these requirements by lifting 2D semantic segmentations from pretrained vision models into a 3D radiance field that jointly encodes geometry, appearance, and per-class semantic identity. The resulting fields are reconstructed from posed RGB captures of real scenes and support novel-view synthesis, semantic and free-space queries within a single grounded representation. This enables the efficient generation of diverse real-world environments to train and evaluate spatial reasoning models. As an example application, we outline an SRF-driven simulator for an orchard apple-reaching task, in which the radiance field supplies camera rendering, semantic ground truth, and occupancy queries to a physics engine.

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Nico Heider, Michał Jan Włodarczyk, Katarzyna Wasielewska-Michniewska, Przemysław Hołda, Martin Schieck, Marcin Paprzycki, Maria Ganzha, Bogdan Franczyk. 2026-08-13. Semantic Radiance Fields as Simulators for Spatial Reasoning in Real-World Scenes. https://arxiv.org/abs/2608.13095

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