Filament models are used for geometries where location and orientation of particles can be defined with relation to tubular estructures.
The usual way of handling them is by opening a small fraction of a tomogram inside dtmslice and mark manually positions that will be used to define a "backbone". Loosely speaking, we call the " backbone of the filament" to the series of ordered points that arise from defining successive orthogonal sections along the path of the filament and picking the central point.
Different models are available for the different relationships between the "backbone" of the filament and the locations and positions of the particles to be cropped.
The input points in a filament model are used to define a smooth interpolant called backbone.
Clicking input points in dtmslice
Different models are provided to account for different ways of relating particles to the backbone.