Automatic extraction of actin networks in plants
Fig 3
A visualisation of several of the measurements we define to quantify the actin network. The ROI size is measured as the area encompassed by the black line of the outer bounding box and is used in the calculation of densities such as the skeleton and branch point density. The cell orientation is measured as the angle of the bounding box relative to the horizontal axis. The curvature, both the signed filament curvature and the unsigned filament curvature, are averaged over the whole length of each filament and measured via a series of three points separated by a characteristic length scale, λ. The deviation measures the average distance between a filament and a straight line connecting the end points. The filament width is defined for each filament as an average over the filament length. The filament angle, θf, is measured relative to the major cell axis and is calculated both as a 2D and 3D (estimated) version. The branch angle, θb, is measured at every branch point and measures the deviation of the branch from the main filament; again, there is a 2D and 3D (estimated) version. Finally, the branch ratio is the number of branch points divided by the number of labelled filaments.