Orthoimages can be used as control information to determine the exterior orientation of new aerial images. For that purpose, the image displacements on aerial images due to photographic tilt and topographic relief (including the height of topographic objects) should be exactly removed to generate ”true” orthoimages. Thus the correct geometrical and radiometric information can be provided from them for control information. However it is always time-consuming and labour-intensive to capture the accurate heights of terrain area for removing the image displacements from topographic relief. Therefore, this paper will propose a methodology to generate the orthoimage patches from multiple aerial images without capturing accurate terrain heights. In the proposed method, a concept of floating plane, similar to the concept of floating mark, will be presented to produce several orthoimage candidate sets for a terrain area at some height range from multiple aerial images. Each orthoimage candidate set consists of several related orthoimage patches for a terrain area at some specific height. Subsequently, a procedure will be developed to decide an optimal orthoimage set for this terrain area among those orthoimage candidate sets. While the optimal orthoimage set is decided, the height information is also determined. After that, a unique orthoimage patch for this terrain area will be fused from this optimal orthoimage set. The relevant assessment of accuracy is also discussed and conducted in this paper. The preliminary experiments prove the feasibility of the proposed method.