1. A method of operating a surveillance system having a display unit configured to display a surveillance image, the method comprising: acquiring the surveillance image from at least one acquisition device; setting a surveillance event that includes selecting a desired surveillance object indicating an attribute of the surveillance event and input information including at least one of text, a symbol and a number; displaying the selected surveillance object and information with the acquired surveillance image on the display unit; analyzing the acquired surveillance image to determine whether the set surveillance event has occurred; determining, based on the acquired surveillance image, that the set surveillance event has occurred; and responsive to a determination that the set surveillance event has occurred, performing an indicating operation in the surveillance system.