An ASCII format that contains the same amount of information as NDskl files, but organized in a different way. In particular, filaments are not described as lists of segments but rather each filament is described by an origin node, a destination node, and a set of sampling points.

NDskl_ascii format
ANDSKEL header
ndims the number of dimensions
#comments go here OPTIONAL: should start with '#' if present (the 80 first characters are read and stored).
BBOX [x0_1 .. x0_d] [delta_1 .. delta_d] OPTIONAL: the bounding box, defined by the 'ndims' coordinates of the origin 'x0' and extent 'delta'.
[CRITICAL POINTS] Marks the beginning of the critical points section
ncrit The number of critical points (CP)
type pos[0] ... pos[ndims-1] value pairID boundary Info on the first CP: critical index, position, value, index of CP in the persistence pair, 0 if not on the boundary
nfil The number of filaments connected to this CP
destId[0] filId[0] Info on the first filament: index of the CP at the other extremity of the filament, and index of the filament (see filaments table below)
... One line for each filament connecting on the CP
destId[nfil-1] filId[nfil-1] Information on the last filament
.....
..... one blue block for each CP.
.....
[FILAMENTS] Marks the beginning of the filaments section
nfil Total number of filaments
CP1 CP2 nSamp index of the CP at the extremity of the first filament and number of sampling points
P[0][0] ... P[0][ndims-1]position of the first sampling point of first filament.
...One line for each sampling point of first filament.
P[nSamp-1][0] ... P[nSamp-1][ndims-1]Position of the last sampling point
.....
..... one blue block for each filament.
.....
[CRITICAL POINTS DATA] Marks the beginning of the CP data section
NF Number of fields associated to each CP.
CP_DATA_FIELD_NAME_1 Name of the first field
...
CP_DATA_FIELD_NAME_NF Name of the last field
val_1[0] ... val_NF[0] Value of each field for first CP
...
val_1[N_CP-1] ... val_NF[N_CP-1] Value of each field for last CP
[FILAMENTS DATA] Marks the beginning of the filaments data section
NF Number of fields associated to each sampling point of each filament.
FIL_DATA_FIELD_NAME_1 Name of the first field
...
FIL_DATA_FIELD_NAME_NF Name of the last field
val_1[0][0] ... val_NF[0][0] field values for first sampling point, first filament
...
val_1[0][nSamp[0]] ... val_NF[0][nSamp[0]] field values for last sampling point, first filament
.....
..... one blue block for each filament.
.....