I. Introduction
Crowd behaviour analysis is an important matter of concern, in terms of both safety and security. Crowd formations are present in streets, public events, concerts, airports, religious pilgrimages, marathons etc., these venues are in danger of crowd disaster occurrences. Video surveillance has been increasing in many environments to enhance security and prevent disastrous situations. Consequently, a substantial amount of data is generated from multiple sources, therefore overwhelming surveillance operators. Automation of crowd behaviour analysis with limited human supervision is required to enable smarter and safer environments. To achieve this, specific information is extracted from surveillance footage using computer vision tasks to automatically understand the behaviour of a crowd.