A Virtual Assistant for Architectural Design in a VR Environment
Paper · 2026 · Ander Salaberria, Oier Ijurco, Markel Ferro et al.
Summary
Editing Building Information Modeling (BIM) files usually requires expert software skills. This slows down iterative architectural prototyping and shuts out non-specialists. The authors present VR-ARCH, a voice-driven assistant that lets users inspect and change a BIM-based building while immersed in virtual reality.
Spoken requests are transcribed and passed to a ReAct-style Router LLM. At each step, the Router picks one of three prompt-engineered tools:
- a Modifier, which writes Python code against a custom Unreal Engine sandbox API;
- a Querier, which writes Cypher queries over BIM data stored in Neo4j;
- an ID Retriever, which locates objects using spatial cues relative to the user's position.
Chaining these tools supports composite requests, such as asking for the material of a particular wall. Replies are spoken back via text-to-speech. Evaluation with human judges and LLM-as-a-judge shows that LLMs can answer questions and carry out modifications reliably, with quality rising as model size grows. Hallucinations and inefficient routing remain open problems. Code and data are public, and the setup also doubles as a benchmark for agentic behaviour in realistic settings.
Key points
- The pipeline has six components: speech-to-text, the ReAct Router, the Unreal Engine sandbox with its Python API, the Neo4j graph database (Cypher), the three tools (Modifier, Querier, ID Retriever) and text-to-speech.
- The sandbox API can recolor, move, hide or reveal objects, control the camera, and add, transform or delete props. Spatial commands take the user's position into account.
- Each LLM is adapted only through prompting, using task definitions, API docs or graph schemas, and few-shot examples; there is no fine-tuning.
- In the step analysis, most correct answers use the optimal number of steps. One extra step can still succeed, but accuracy falls sharply with longer trajectories.
- In a case study, a 32B model recovers from a wrong first tool choice, whereas a 4B model loops without finishing. Stated limitations are that extending the sandbox API takes manual work, the system has no visual grounding, and results depend on BIM file quality.
Institutions
Fields, topics and concepts
📚 Shelves 7The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 worksEngineering · 133 worksHuman-Computer Interaction · 141 worksArchitecture · 2 works
Cite
Cite as Ander Salaberria, Oier Ijurco, Markel Ferro, Jiayuan Wang, Iñigo Vilá Muñoz, Roberto de Ioris, Jeremy Barnes and Oier Lopez De Lacalle. 2026. A Virtual Assistant for Architectural Design in a VR Environment. Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 3: System Demonstrations).
@inproceedings{salaberria2026virtual,
title = {{A Virtual Assistant for Architectural Design in a VR Environment}},
author = {Ander Salaberria, Oier Ijurco, Markel Ferro, Jiayuan Wang, Iñigo Vilá Muñoz, Roberto {de Ioris}, Jeremy Barnes and Oier Lopez {De Lacalle}},
booktitle = {Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 3: System Demonstrations)},
year = {2026},
doi = {10.18653/v1/2026.eacl-demo.38},
url = {https://doi.org/10.18653/v1/2026.eacl-demo.38}
}References
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