Multiscale fractal dimension applied to tactical analysis in football: A novel approach to evaluate the shapes of team organization on the pitch

PLoS One. 2021 Sep 1;16(9):e0256771. doi: 10.1371/journal.pone.0256771. eCollection 2021.

Abstract

The aim of this study was to evaluate different shape descriptors applied to images of polygons that represent the organization of football teams on the pitch. The effectiveness of different shape descriptors (area/perimeter, fractal area, circularity, maximum fractal, rectangularity, multiscale fractal curve-MFC), and the concatenation of all shape descriptors (except MFC), denominated Alldescriptors (AllD)) was evaluated and applied to polygons corresponding to the shapes represented by the convex hull obtained from players' 2D coordinates. A content-based image retrieval system (CBIR) was applied for 25 users (mean age of 31.9 ± 8.4 years) to evaluate the relevant images. Measures of effectiveness were used to evaluate the shape descriptors (P@n and R@n). The MFD (P@5, 0.46±0.37 and P@10, 0.40±0.31, p < 0.001; R@5, 0.14±0.13 and R@10, 0.24±0.19, p < 0.001) and AllD (P@5 = 0.43±0.36 and P@10 = 0.39±0.32, p < 0.001; R@5 = 0.13±0.11 and R@10 = 0.24±0.20, p < 0.001) descriptors presented higher values of effectiveness. As a practical demonstration, the best evaluated shape descriptor (MFC) was applied for tactical analysis of an official match. K-means clustering technique was applied, and different shapes of organization could be identified throughout the match. The MFC was the most effective shape descriptor in relation to all others, making it possible to apply this descriptor in the analysis of professional football matches.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Athletes
  • Brazil
  • Data Analysis
  • Fractals
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Models, Theoretical*
  • Soccer*
  • Software
  • Video Recording
  • Young Adult

Associated data

  • figshare/10.6084/m9.figshare.14249456.v1

Grants and funding

CNPq (protocol number 446548/2014-6); Fundação Araucária (protocol number 25372/2013); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001; São Paulo Research Foundation (FAPESP) grant# 2016/50250-1 -2017/20945-0 - 2018/19007-9; Superintendência de Ciência, Tecnologia e Ensino Superior - SETI (03/2021); State University of Londrina, Londrina, Brazil - PROPPG-UEL (03/2021). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.