author = "Almeida, Ana Paula Gon{\c{c}}alves S. de and Vidal, Flavio de 
          affiliation = "{Programa de P{\'o}s-Gradua{\c{c}}{\~a}o em Sistemas 
                         Mecatr{\^o}nicos - Universidade de Bras{\'{\i}}lia} and 
                         {Departamento de Ci{\^e}ncia da Computa{\c{c}}{\~a}o - 
                         Universidade de Brasilia}",
                title = "Classifica{\c{c}}{\~a}o n{\~a}o-supervisionada de eventos em 
                         imagens de videomonitoramento baseada em altas frequ{\^e}ncias do 
                         fluxo {\'o}tico diferencial",
            booktitle = "Proceedings...",
                 year = "2015",
               editor = "Rios, Ricardo Araujo and Paiva, Afonso",
         organization = "Conference on Graphics, Patterns and Images, 28. (SIBGRAPI)",
            publisher = "Sociedade Brasileira de Computa{\c{c}}{\~a}o",
              address = "Porto Alegre",
             keywords = "event classification, motion analysis, optical flow.",
             abstract = "Events related to vandalism and violence often occur in crowded 
                         environments and mostly in unstructured environments (dynamic). 
                         The use of security cameras in crowd monitoring analysis for 
                         anomaly detection and alarms could be an efficient and inexpensive 
                         method. The goal of this paper is to build an unsupervised 
                         classification method to abnormal events that is robust and 
                         stable. The main idea is based on analysis of Fourier Transform's 
                         high-frequency spatial components features of optical flow, 
                         allowing the detection of abnormal acts in surveillance videos. 
                         Preliminary results show that the proposed methodology is capable 
                         of successfully execute the process of detection, permitting the 
                         development of an efficient recognition stage for future works.",
  conference-location = "Salvador",
      conference-year = "Aug. 26-29, 2015",
             language = "pt",
                  ibi = "8JMKD3MGPBW34M/3JRJS95",
                  url = "",
           targetfile = "sibgrapi-cameraready.pdf",
        urlaccessdate = "2021, Dec. 01"