ProScene: Progressive 3D Indoor Scene Generation with Spatial-Validity Guidance

Indoor scene synthesis methods commonly generate a layout where objects are represented by oriented 3D bounding boxes, followed by mesh retrieval or generation based on box parameters to complete the scene. This often leads to output with spatial violations, including collisions and out-of-bounds errors. Because boxes are too coarse to represent complex shapes or interleaving objects, true violations cannot be reliably distinguished from valid configurations where bounding boxes overlap but the meshes do not, limiting accurate guidance toward spatial validity. We therefore propose ProScene, a retrieval-free multi-stage model that progressively generates 3D scenes through a box$\to$cuboid$\to$mesh hierarchy. ProScene first produces a coarse box layout in stage 1, then employs a coupled layout-cuboid diffusion model in stage 2 to jointly refine the layout and generate object cuboids, with bidirectional feature exchange allowing both representations to co-evolve during denoising. We further apply cross-scale spatial-validity guidance, using boxes for efficient spatial error assessment and cuboids for more accurate evaluation. The resulting violation energies are used to guide the output toward spatial plausibility. Finally, stage 3 conditions an object generator on the predicted cuboids and semantic information to synthesize detailed meshes. This hierarchy provides an explicit structural bridge between coarse scene arrangement and detailed object geometry, enabling spatial-violation-aware scene generation.