Resource-Constrained 3D Volume Estimation of Lunar Regolith Particles from 2D Imagery for In-Situ Dust Characterization in a Lunar Payload

Future lunar exploration efforts rely on an improved understanding of regolith behavior, as evidenced by the adhesion problems encountered during the Apollo missions. The Lunaris Payload, a compact lunar instrument developed in Poland, aims to assess the adhesion of lunar regoliths to various materials using an optical method chosen to meet strict mass constraints. We introduce and validate a resource-constrained optical method to estimate three-dimensional volumes of lunar regolith particles from two-dimensional imagery, using high-resolution micro-CT as ground truth. The approach supports in-situ surface characterization and dust-related risk assessment under the mass and power constraints typical of small payloads. Micro-CT scans were used to establish accurate reference volumes, and multiple geometric approximation methods were applied, including spherical, ellipsoidal, and cylindrical models, to derive volume estimates from a 2D representation. Comparative analyses demonstrate that ellipsoid-based models, particularly those that incorporate a fixed aspect ratio, provide the most accurate volume estimations. These findings offer a practical in situ methodology for analysing the volumes of regolith particles, thus advancing the capacity of the Lunaris mission to characterise lunar adhesion of regolith particles and supporting broader efforts in lunar resource utilisation and habitat construction. To our knowledge, this is the first benchmarking of six 2D-to-3D volume models against micro-CT for lunar regolith adhesion applications. Our findings demonstrate that ellipsoid-based methods achieve the best results, offering a validated, efficient technique for in-situ dust characterization critical for future lunar missions.