Abstract: Modeling trees in a plausible and fast way is a challenge in virtual reality. A new sketch-based tree modeling method is presented in this paper. A realistic 3D tree model can be generated automatically from freehand sketches of users: sketches of main branches and crown silhouette on one input image, and sketches of two boundary branches and crown silhouette on anther input image. Input sketches are used to describe two vertical sides of a tree. 3D main branches are constructed by distribution control on multiple planes. Small branches are generated within the crown silhouettes based on self-similarity. Technical contribution of this work is that a new distribution control theory is proposed and used for branch depth setting, as makes the modeling method simple and fast. Experiments demonstrate that realistic 3D tree models with even branch distribution could be quickly obtained through simple sketching.