The aim of this study was to present a validation protocol using a global positioning system with real-time differential correction (dGPS) to assess the validity and the reliability of a semi-auto tracking software (TACTO) used to quantify the movement patterns of football players. In order to obtain the 2D coordinates of the movements of a player from the virtual coordinates, the TACTO software was used twice, first for calibration (the virtual coordinates of a set of reference points at the game surface were collected, corresponding to points with known real coordinates) and then for digitalization (reconstruction of coordinates). The reconstruction of virtual coordinates of the player into real coordinates was carried out using DLT-2D, with algorithms developed in MATLAB` software routines. The coordinates obtained by this methodology were compared to the coordinates obtained by dGPS receiver. The validity and the intra-user and inter-users reliability of the methodology used were proved by all the statistical parameters used (the relative technical error of measurement (ETM), the Pearson coefficient (r), and the intra-class correlation coefficient ( ICC)).
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