Lithology-specific morphological characterization and constraint-based spherical harmonic generation of Chang’e-6 Lunar Regolith particles

Realistic particle shape representation is important for lunar regolith characterization and particle-based numerical models, but natural lunar samples are limited and lithologically heterogeneous. This study proposes a lithology-informed spherical harmonic framework to represent, generate, and screen Chang’e-6 lunar regolith particles for numerical applications. Agglutinate, basalt, and breccia particles were reconstructed from three-dimensional data and characterized using morphological descriptors, including aspect ratio, sphericity, convexity, and overall regularity. Spherical harmonic coefficients were then extracted and statistically used to generate virtual particles with lithology-dependent shape characteristics. To avoid unrealistic geometries, a multi-level morphological constraint system was established, including descriptor ranges, principal-axis-ratio domains, two-dimensional coupled morphology spaces, S − C X linear consistency, and OR constraints. The screened particles preserved the major morphological distributions, principal-axis proportions, and coupled descriptor relationships of natural particles, and showed good agreement with reference lunar regolith morphology spaces. This framework enables scale-dependent morphological analysis of Chang’e-6 lunar regolith particles (70–500 μm) and provides a morphology-based particle library that balances realistic lunar particle representation and computational efficiency.