Fig. 6.

Definitions of Bingham distribution parameters. a Parameters describing the distribution’s centre. ${\mathit{\Theta }}_{\mathrm{h}}$ and ${\mathit{\Theta }}_{\mathrm{t}}$ are the centre’s helix and transverse angles. b Parameters describing the distribution’s dispersion. ${\mathit{\kappa }}_1$ and ${\mathit{\kappa }}_2$ describe the distribution’s concentration along two orthogonal directions. The more negative a $\mathit{\kappa }$ is, the narrower the distribution is in the respective direction (Onstott 1980). ${\mathit{\Theta }}_{\mathrm{i}}$ is the angle that the principal spread direction (corresponding to ${\mathit{\kappa }}_2$) makes with the axial–circumferential plane. In this example, ${\mathit{\Theta }}_{\mathrm{h}}={30}^{\circ }$, ${\mathit{\Theta }}_{\mathrm{t}}={10}^{\circ }$, ${\mathit{\kappa }}_1=-30$, ${\mathit{\kappa }}_2=-10$, and ${\mathit{\Theta }}_{\mathrm{i}}=-{25}^{\circ }$. a axial