在影像資訊系統中，為了使影像檢索達到比對更精確與查詢更快速的目標，發展一套良好的空間知識表示法更顯得重要，透過空間知識表示法所儲存的空間資訊作為影像索引，可支援空間推論與相似檢索，以滿足使用者的需求。而RS-string與2D Z-string乃著名的空間知識表示法，RS-string主要植基於極座標系統，能夠達到旋轉不變之特性，而植基於卡笛生座標系統的2D Z-string則藉由零切割機制，不僅縮減字串長度且加入物件大小、位置、距離等計量資訊，兩者都克服了2D string相關研究的一些缺點。然而，我們發現在某些情況下，RS-string仍有精確度不足之處，以致會做出相似比對的誤判。因此，在本文中，我們以RS-string為基礎，排除在極座標系統中引用2D Z-string概念的困難，提出RS+-string空間知識表示法，同時擁有了RS-string與2D Z-string的優點，進而能夠達到更精確的空間推論與相似檢索。In image information system, it is important to develop a well spatial knowledge representation in order to attain the goal that image retrieval can be much precisely and quickly. By spatial knowledge representation to store the spatial information, it can support spatial reasoning and similarity retrieval to help users query image to satisfy their request. RS-string and 2D Z-string are the two famous spatial knowledge representation. RS-string is based on polar coordinate system, so it can arrive at rotation-invariant. But, 2D Z-string is based on Cartesian coordinate system, its feature not only reduces the length of string by using zero-cutting but also records the metric information that includes the size of object、location and distance. Both of them overcome the drawbacks of the relative researches of 2D string. However, we find that RS-string can not attain much precisely similarity retrieval in some condition, so it may result in misjudging of similarity retrieval. Thus, in this paper, we propose a spatial knowledge representation which is based on RS-string and we name it as RS+-string. At the same time, we overcome the difficulty to apply the concept of 2D Z-string to the polar coordinate system. In addition, RS+-string also has the advantages of RS-string and 2D Z-string, therefore it can attain much precisely spatial reasoning and similarity retrieval.
