SynCity 3000: Bootstrapping Scene-Scale 3D Diffusion

2026-07-06

AI Summary

Existing methods struggle to generate large-scale 3D scenes that simultaneously maintain global structural consistency and support fine-grained layout control. This work presents the first extension of single-image 3D generation models to the scene scale, introducing a convolutional 3D diffusion architecture and a dedicated synthetic data engine to mitigate the scarcity of real-world 3D scene datasets. By reformulating the image-to-3D generator as a convolutional operator and fine-tuning it on synthetically generated scenes, the proposed approach enables the generation of arbitrarily sized and complex 3D environments that are both geometrically detailed and structurally coherent. The method significantly outperforms existing approaches across diverse layouts and semantic prompts, demonstrating strong controllability and scalability in 3D scene synthesis.

Abstract

We present SynCity 3000, a framework for generating 3D scenes that are globally coherent while enabling fine-grained layout control. Building on the ability of current image-to-3D generators to produce complex 3D assets from a single image, we extend this capability to the scale of entire scenes by adapting the generator to be applicable as a convolutional operator. We achieve this by fine-tuning the model on scene-like data generated by a new synthetic data engine, which we propose to address the scarcity of 3D scene data for training. The convolutional generator is then applied to a dimetric image of the entire scene, generated from the user prompt, resulting in 3D scenes of arbitrary size and complexity. Across diverse prompts and layouts, SynCity 3000 produces large, coherent, and detailed scenes, addressing the shortcomings of prior approaches to 3D scene generation.

Problem

• 3D scene generation
• global coherence
• layout control
• data scarcity
• scene-scale synthesis

Innovation

• 3D scene generation
• diffusion models
• convolutional generator
• synthetic data engine
• layout control