Biological structure and function are closely linked, with functional clues often concealed within intricate three-dimensional details of the structure. Such details in branching, fibrous and porous biological assemblies can be investigated at multiple scales using volumetric imaging. However, 3D visualisations alone do not provide a quantitative assessment of specimen architecture. Directional quantification of structural attributes such as texture — reflecting orientation and co-alignment (anisotropy) of structural elements — is important for deciphering structure-function relationships, predicting mechanical behaviour, and optimising designs. We developed VectoRose — a new open-source package for visualisation and quantitative analysis of 3D vector data using spherical histograms and directional statistics — and we analyse here three case studies of biological assemblies (branching, fibrous and porous). The outputs produced by VectoRose provide quantitative insights into structure-function relationships in global and local architectural motifs. For branching structures, a comparison of the transport network between a bay leaf and a reindeer lichen quantifies the difference between planar and volume-filling dendritic patterns. Statistical analysis of the 3D fibrous assembly in the membrane of a bird and a gecko eggshell may reflect the evolutionary divergence in egg incubation strategies. Finally, an investigation of the porous trabecular bone pattern in the sheep femur offers a quantitative approach for studying structure-function relations governing bone biomechanical adaptation. With robust statistical descriptions of 3D anisotropy applicable to homologous or disparate structures alike, we foresee that quantitative texture analysis will confer reproducibility, together with subtlety and nuance, to structure-function studies in other domains of materials research.
Rudski et al. (Wed,) studied this question.