A computer-implemented method of determining whether an alert system recognises an unusual situation as such and, if required, triggers an alert signal, which first image sensor is a virtual sensor and has a virtual sensor range, and which sensor range comprises a first location, wherein image sensor model data is generated from input data such as maps of an area, which image sensor model data describes at least the virtual sensor range of the first image sensor in the shape of a three-dimensional model, wherein simulation data as image data comprising the image sensor model data and object movement data of a person as an object is generated in a calculating unit, wherein the image sensor model data is devoid of the moved person, wherein the object movement data continuing for a timespan comprises image data generated at a second time, of a real movement of the person at a second location determined using a real second image sensor or a virtual movement of the person at a virtual second location, characterised in that, the object movement data describes the movement of the person by individual movements of selected subareas of said person, such as their arms, legs, head, wherein the simulation data describing either a common event or an unusual event is forwarded to an alert unit processing image data, wherein, in the alert unit, the situation described by the simulation data comprising the image sensor model data and the object movement data and taking place in the sensor range is classified either as a common event or as an unusual event by using pattern recognition methods and/or object recognition methods, wherein the object movement data is classified in consideration of the individual movements of the person's subareas, which alert system issues an alert signal in the case of an unusual event, allowing verification based on the alert signal issued as to whether an alert system triggers an alert signal in the case of simulation data which comprises an unusual event. whether an alert system recognises an unusual situation as such and, if required, triggers an alert signal, which first image sensor is a virtual sensor and has a virtual sensor range, and which sensor range comprises a first location, wherein image sensor model data is generated from input data such as maps of an area, which image sensor model data describes at least the virtual sensor range of the first image sensor in the shape of a three-dimensional model, wherein simulation data as image data comprising the image sensor model data and object movement data of a person as an object is generated in a calculating unit, wherein the image sensor model data is devoid of the moved person, wherein the object movement data continuing for a timespan comprises image data generated at a second time, of a real movement of the person at a second location determined using a real second image sensor or a virtual movement of the person at a virtual second location, characterised in that, the object movement data describes the movement of the person by individual movements of selected subareas of said person, such as their arms, legs, head, wherein the simulation data describing either a common event or an unusual event is forwarded to an alert unit processing image data, wherein, in the alert unit, the situation described by the simulation data comprising the image sensor model data and the object movement data and taking place in the sensor range is classified either as a common event or as an unusual event by using pattern recognition methods and/or object recognition methods, wherein the object movement data is classified in consideration of the individual movements of the person's subareas, which alert system issues an alert signal in the case of an unusual event, allowing verification based on the alert signal issued as to whether an alert system triggers an alert signal in the case of simulation data which comprises an unusual event.