The TRC file format created by Motion Analysis serves double duty. It is the raw output from their full body motion capture system and it is also used as the output format for their realtime face tracker. In the case of the face tracker, Z is always zero for each marker.

As with all tracking formats the markers have only position data that is global. The TRC format contains a header section and a motion section. Markers are named and should be referenced by their name inside your application.

The file consists of two sections, the header and the motion section. The first line of the header section contains the keyword "PathFileType" followed by the number of the path type. This same line also contains the token (X/Y/Z) [I don't know what this is for, I'll check with MAC, I just ignore it] followed by the last element on the line which is the full path and filename of the data file. For just reading the motion data you don’t need this information.