ReGDiff: Guided Diffusion in Regulated Latent Space for Exploring Metamaterial Voxel Geometry
Organizations: Department of Computer Science Virginia Tech Blacksburg, VA 24061 · Meta Menlo Park, CA 94025
Abstract
Metamaterials are artificially engineered structures whose mechanical and physical behaviors are strongly shaped by geometry rather than composition. Voxel representation provides a unified format for metamaterial geometry generation, as it can express diverse classes such as truss, shell, and porous structures within a single cubic discretization. However, voxel-based generation faces a plausibility-novelty trade-off: staying close to known geometries helps preserve geometric regularities, while moving away from them is necessary for novelty but may produce degenerate geometries. To address this challenge, we propose REGDIFF, a generative framework that couples voxel representation with latent space regulation and guided diffusion. REGDIFF introduces a repel-and-sink (RAS) mechanism to smooth the latent distribution of plausible geometries, and short-range repulsion (SRR) guidance to discourage generation overly close to known samples while maintaining geometric plausibility. We further contribute a voxel-based benchmark covering truss- and shell-type metamaterial geometries, together with an evaluation module for geometric plausibility, novelty, and diversity. Experiments show that REGDIFF outperforms voxel-based generative baselines, achieving +8.9% in geometric plausibility, +46.4% in novelty, and +128.6% in diversity on average across two datasets. These results suggest that REGDIFF is a strong geometry candidate generator for downstream evaluation. Our code is provided at https://github.com/wzhan24/ReGDiff.
Figures & tables
| Approaches | Geometric Plausibility Scores | Novelty Score | Diversity Score | |||
|---|---|---|---|---|---|---|
| Mean | ||||||
| MetaTruss (ours) | ||||||
| DiT-3D ( Mo et al. (2023) ) | 0.358 | 0.248 | 0.500 | 0.369 | 0.003 | 0.010 |
| Y. Yang et al. ( Yang et al. (2024) ) | 0.800 | 0.585 | 0.494 | 0.626 | 0.163 | 0.158 |
| XCube ( Ren et al. (2024) ) | 0.506 | 0.525 | 0.522 | 0.518 | 0.000 | 0.004 |
| Trellis ( Xiang et al. (2025) ) | 0.081 | 0.063 | 0.133 | 0.092 | 0.000 | 0.001 |
| Approaches | Geometric Plausibility Scores | Novelty Score | Diversity Score | |||
|---|---|---|---|---|---|---|
| Mean | ||||||
| Case 1 (RAS + vanilla DDPM) | 0.753 | 0.632 | 0.885 | 0.757 | 0.208 | 0.336 |
| Case 2 (w/o reg + SRR Diff.) | 0.873 | 0.801 | 0.295 | 0.656 | 0.014 | 0.011 |
| Case 3 (full framework) | 0.718 | 0.487 | 0.969 | 0.725 | 0.296 | 0.420 |
| Approaches | Geometric Plausibility Scores | Novelty Score | Diversity Score | |||
|---|---|---|---|---|---|---|
| Mean | ||||||
| Increase AE Param. Num. | 0.753 | 0.471 | 0.977 | 0.734 | 0.308 | 0.411 |
| Decrease AE Param. Num. | 0.688 | 0.479 | 0.953 | 0.707 | 0.280 | 0.413 |
| Increase diff. Param. Num. | 0.705 | 0.474 | 0.936 | 0.705 | 0.330 | 0.444 |
| Decrease diff. Param. Num. | 0.722 | 0.493 | 0.955 | 0.723 | 0.286 | 0.409 |
| Original setting | 0.718 | 0.487 | 0.969 | 0.725 | 0.296 | 0.420 |
Appendix figures & tables6 assets
Supplementary material from the paper’s appendix.
Appendix
| Approaches | Geometric Plausibility Scores | Novelty Score | Diversity Score | |||
|---|---|---|---|---|---|---|
| Mean | ||||||
| Case 1 (RAS + vanilla DDPM) | 0.935 | 0.884 | 0.930 | 0.916 | 0.305 | 0.625 |
| Case 2 (w/o reg + SRR Diff.) | 0.910 | 0.795 | 0.842 | 0.849 | 0.237 | 0.477 |
| Case 3 (full framework) | 0.923 | 0.856 | 0.978 | 0.919 | 0.380 | 0.783 |
| Approaches | Geometric Plausibility Scores | Novelty Score | Diversity Score | |||
|---|---|---|---|---|---|---|
| Mean | ||||||
| Increase AE Param. Num. | 0.915 | 0.858 | 0.985 | 0.919 | 0.362 | 0.711 |
| Decrease AE Param. Num. | 0.894 | 0.823 | 0.963 | 0.893 | 0.363 | 0.742 |
| Increase diff. Param. Num. | 0.920 | 0.810 | 0.953 | 0.894 | 0.389 | 0.781 |
| Decrease diff. Param. Num. | 0.907 | 0.852 | 0.956 | 0.905 | 0.359 | 0.775 |
| Original setting | 0.923 | 0.856 | 0.978 | 0.919 | 0.380 | 0.783 |
| Approaches | Time (s) |
|---|---|
| DiT-3D ( Mo et al. (2023) ) | 326 |
| Y. Yang et al. ( Yang et al. (2024) ) | 28 |
| XCube ( Ren et al. (2024) ) | 94 |
| Trellis ( Xiang et al. (2025) ) | 5 |
| 3D-CDM ( Zheng et al. (2025) ) | 813 |
| ReGDiff (ours) | 31 |