Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:…matrix transformed the global coordinate system into a local orthogonal coordinate system using a direct frame by frame method (Scurr et al., 2010), identifying the suprasternal notch as the origin and establishing the right and left nipple coordinates relative to the trunk (Scurr et al., 2010).
Category: