Control points are used for 2D and 3D alignment, and to constrain 3D scene
models. Control point data is loaded from a control point file. Scripts to
generate and manipulate control point files are included in the
scripts directory of the source distribution; the file
specification is outlined in the final section below.
The --cpf-load= option is used to load data from a control point file.
--cpf-load=<f> Load control point data from file <f> [0.8.1 and later]
The version 0 control point file format consists of a version command followed by a sequence of control points, with one control point per line of the file.
V 0 Control Point 1 Control Point 2 Control Point 3 . . .
Control points can be one of three types:
Type A control points specify a sequence of 2D points, one for each frame, where each point is specified as a pair of floating point numbers. If there is no data for a frame, then "nan" should be specified. E.g.:
A 20 30 nan nan 10 10 10 15 A 23 22 25 25 nan nan nan nan
Type B control points specify a 3D coordinate. E.g.:
B 10 30 -400 B 10 15 -425
Type C control points specify both 2D and 3D data. There is a single 3D point specified, as well as one 2D point for each frame. The 3D point appears at the end of the line. E.g.:
C 20 30 nan nan 10 10 10 15 10 30 -400 C 23 22 25 25 nan nan nan nan 10 15 -425