Abstract
We develop a graphical user interface for defining events in a framework for detecting high-level surveillance events from a video stream, as the language used for the events may be too complex for an ordinary user. The language is based on relational algebra extended by intervals, introducing operators whose temporal constraints are described using the well-known Allen's interval relationships. The user interface captures intervals in a descriptive way, supporting the user in providing the missing parameters in a step-by-step manner. In the background, the system checks the user input for consistency and automatically transforms it into relational algebra expressions.