In this paper, we propose a novel synthesis technique for BTFs. A BTF (bidirectional texture function) is a 6D function which can represent appearances of a texture under arbitrary view and lighting conditions. Until now, several approaches of BTF synthesis have been researched. For ordinary textures, patch based methods are promising techniques for texture synthesis. However, it has not been effectively tried to BTFs yet. This is mainly because data size of BTFs is so large and it is not easy to apply the techniques to BTFs. Further, efficient rendering of BTFs is still under research. In this paper, we extend a patch based synthesis technique for BTFs by utilizing compact representation of BTFs. In addition, we propose a novel technique to render the synthesized BTFs efficiently. With our proposed method, we can successfully and effectively render objects with complicated surfaces under arbitrary sizes.