RETIRE3D — WHERE RESOLUTION LIVES: LOCAL SCALE COMPLETION FOR COARSE-TO-FINE 3D GENERATION

Coarse-to-fine 3D generators commonly advance predicted surface regions through a shared finest generation stage. This uniform allocation conflicts with a basic property of 3D geometry: geometric complexity is highly non-uniform in space. Broad, smooth surfaces can often be determined at a coarse scale, whereas thin structures, sharp boundaries, holes, and junctions demand finer precision. The benefit of additional fine-stage computation can therefore vary substantially across regions. We identify this conflict as a mismatch between uniform computational resolution and local geometric demand, and formulate Local Scale Completion: fine-scale computation should follow remaining local geometric demand. We introduce Retire3D, a training-free framework that instantiates this principle through spatially selective evaluation within the high-resolution stage, retaining all latent coordinates. Retire3D uses coarse-stage signals to initialize a fixed evaluation partition, while all fine-scale latent states continue to evolve and provide attention context. History-based propagation supplies unevaluated velocities, and residual checks schedule full reevaluations. The complete spatial representation enters the native downstream pipeline. Experiments on Direct3D-S2 and TRELLIS.2 assess end-to-end efficiency and fidelity to native generation. On Direct3D-S2, Retire3D achieves a native-geometry fidelity score of .927 versus .634 for backbone-adapted Fast3Dcache, a 46.2% relative improvement. With temporal caching, Retire3D achieves a 1.528× end-to-end speedup over native generation on TRELLIS.2.