Sketch based L-systems for tree modeling in virtual reality

This thesis proposes a new method for creating tree assets in virtual reality for digital content that combines a sketch-based approach, with a procedural branching system.Sketch-based modeling in virtual reality offers the possibility of quick iteration andcreation of models while a procedural system can aid realism but also provide a large variety of assets from one model. To demonstrate this concept, a virtual reality prototype for tree modeling that combines sketch-based modeling with L-Systems to generate atree’s branching structure is presented. To achieve the combined approach of sketch-basedmodeling and procedural generation of trees, a 2OL-System, a specialized Lindenmayer System that includes context sensitive rules and parameters, was implemented and adapted to react to the user’s input. This work explores the challenges of implementing an interactive L-System by including the user’s choices as parameters into the contextsensitive and parameterized generation rules of the system. Additionally the benefits and pitfalls are discussed that come with a sketch based interface in virtual reality. A user study was conducted to compare the usability of the prototype with a widely used tree modeling tool, SpeedTree. The results showed that the prototype is comparable to the level of usability as SpeedTree, but with the added benefit of quickly generating tree shapes through sketching. This research contributes to the fields of virtual reality, tree modeling, and sketch-based modeling by introducing a new approach utilizing L-Systems for the quick generation of parameterized tree models.