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The head origin is defined as the midpoint between the LFHD and RFHD markers (also denoted 'Front'). Note that after the head XYZ axes are defined and the static head offset angle is applied, a (-0.84, 0, -0.3) mesh origin offset multiplied by a headscale value (2 * distance between temples) is applied.
The midpoint between the LBHD and RBHD markers ('Back') is also calculated, along with the 'Left' and 'Right' sides of the head from the LFHD and LBHD midpoint, and the RFHD and RBHD midpoint respectively.
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For the dynamic trial processing, the head Offset angle is applied around the Y axis of the defined head segment.
After the head XYZ axes are defined and the static head offset angle is applied, a (-0.84, 0, -0.3) mesh origin offset multiplied by a headscale value (2 * distance between temples) is applied.
Thorax
The orientation of the thorax is defined before the origin. The Z axis, pointing upwards, is the predominant axis. This is defined as the direction from the midpoint of the STRN and T10 to the midpoint of CLAV and C7. A secondary direction pointing forwards is the midpoint of C7 and T10 to the midpoint of CLAV and STRN. The resulting X axis points forwards, and the Y axis points leftwards.
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