**2. Materials and methods**

As described in Section 1, the GOALS system has been specifically developed for the use of an opto‐electronic stereo‐photogrammetric measurement approach within a clinical environ‐ ment. This project stems from over 25 years of biomechanical‐clinical research conducted by our research group having in mind the following three specific 'GOALS':


<sup>2</sup> NaturalPoint Inc., OR, USA.

(3) Represent the results in clinical and intuitive manner, with strict biomechanical princi‐ ples, but at the same time hiding the weight of complex mathematical methods involved.

To meet the above points, we have developed an adjustable body skeleton model, which automatically adapts to the measures of the subject. To allow the use of this method in a simple and quick way in daily clinical practice, the model was designed with the intention to maintain the smallest possible number of body landmarks.
