This ASCII format is a very simple one. It consists in a list of individual segments describing the local orientation of the arcs as well as some limited information on the filament they belong. This may be used for doing statistical analysis of local properties of filaments such as the local orientation of a magnetic field for instance. Note that all the segments are oriented from the lower critical index extremity of the filament they belong toward the other extremity (which does NOT mean that the value is strictly increasing, as local fluctuations of amplitude the persistence threshold are still allowed ... ).
nb: you probably want to use option -breakdown of skelconv before using this format.
| #arc segments | Header |
|---|---|
| #U0 U1 U2 V0 V1 V2 value_U value_V type boundary | Header identifying each column |
| #NDIMS NSEGS | Number of dimensions and number of segments |
| U0 U1 U2 V0 V1 V2 value_U value_V type boundary | The value of the fields for the first segment |
| .... | One such line for each NSEGS segment |
Notations:
- -U_0,..., U_ndims : The coordinates of the first extremity of the segment. It is the one closest to the lowest critical index CP along the filament it belongs to.
- -V_0,..., V_ndims : The coordinates of the second extremity of the segment. It is the one closest to the highest critical index CP along the filament it belongs to.
- -value_U, value_V : Value of the field in U and V.
- -type : the type of arc the segment belongs to. The type of an arc is the minimum critical index of the CP at the extremity of the filament the segment belong to.
- -boundary : value can be 0, 1 or 2 when the segment is inside the domain, on the boundary, or outside (e.g. at infinity)