The entities in reality usually have indeterminate boundary and distribute continuously over space. They are fuzzy objects and cannot be represented by conventional field oriented or object oriented models in GISs. The authors propose the concept of “objects with fuzzy extents” to represent them. Three fuzzy object models are developed to represent fuzzy objects for different situations. The Fuzzy Fuzzy object （FF object） model represents objects that have an uncertain thematic description and an uncertain spatial extent

these objects may spatially overlap each other. The Fuzzy Crisp object （FC object） model represents objects with and uncertain spatial extent but a determined thematic content and the Crisp Fuzzy object （CF object） model represents objects with a crisp boundary but uncertain content. A practical example of coastal geomorphology study is elaborated to demonstrate the practical use of the proposed concepts and models.