影片由一連串連續畫面組成，一個畫面中皆可能有多的物件。在單一畫面中，只包含了在此畫面中物件之間的空間關係的資訊，無法表示影片中物件間空間關係的變化。在本論文中，我們定義在兩個相鄰畫面間物件之間空間關係發生變化稱為空間事件，並提出一個表示這些空間事件的字串，稱為空間事件字串。因此，可以根據此字串推論出影片中物件間的空間關係的變化，使得根據空間事件的影片查詢能有效率得進行。我們提出產生空間事件字串的演算法及根據空間事件的進行影片查詢的方法。 此外，一般而言，在兩個連續畫面中發生空間事件的物件數量是相對的少數。由於在空間事件字串中，只需要記錄發生空間事件的物件而其他沒有產生空間關係變化的物件不必記錄，跟其他字串相比，如此可以大大減少字串的長度，減少字串資料的儲存的需求及處理的時間。 A video is composed of a sequence of frames. A frame may contain multiple objects. In a single frame, it contains the spatial relations between objects in this frame. It does not have information about the change of the spatial relations between objects in the video. In this paper, we define the occurrence of change of the spatial relations between objects between two adjacent frames as the spatial event and propose the spatial event string to represent the spatial event. Hence, the change of the spatial relations between objects can be derived from this string and the video query based on spatial events can be processed efficiently. We would propose the algorithm for the generation of the spatial event string and the way to process the video query based on spatial events. Generally speaking, the number the objects involved in spatial events is relatively small. Since the spatial event string contains only the objects involved in spatial events. Compared with other strings, the length of the string can be reduced dramatically. Consequently, the requirement of the storage and the process time of the string can be reduced.
