Creative Modeling And Animation Of 3D Trees

Trees are ubiquitous in both reality and virtual worlds.As witih the flourishing development and popularity of computer graphics,3D tree models are widely used in urban planning,landscape design,film and entertainment industry,3D games,and even virtual reality.To date,they have played important roles in describing the environment and boosting up either real or virtual atmo-sphere of the scenes.To date,the majority of the existing tree modeling literature mainly focuses on generating photorealistic 3D tree models and natural interactions between trees and their environments.In fact,in order to provide compelling visual effects and enhance immerse experiences of virtual reality,it is necessary to model a series of 3D trees exhibiting special attributes,such as similar yet different features,bizarre geometries and structures,etc.for some special scenarios.In addition,custom stylized tree animations are also required in some occasions to enrich the mysterious atmosphere built in the virtual environment.However,the existing tree modeling methods neither address or tackle the above issues.Therefore,we propose three creative modeling and animation methods specialized for 3D trees.Our goal is twofold:efficiently generating a large number of trees exhibiting diversity in both geometries and topologies and creating custom stylized tree animations.Our main contributions are as follows:1.Targeting on facilitating users ' creativity production,we present the first creative tree mod-eling method,which takes limited trees(both the same and the different species)as input and automatically generates novel trees with varying geometries and topologies through hi-erarchical topology-preserving blending.The core of the proposed method is the fuzzy cor-respondences between tree branches and the topology-aware blending algorithm.In addi-tion,the proposed method also ensures the diversity of the generated trees by employing a stochastic scheduling strategy for the blending tasks.To take one step further,we also de-velop a feasible solution to establish fuzzy correspondences among multiple trees,and design an exploratory modeling interface to support blending among multiple trees.2.Targeting on generating a novel special effects for leafy trees,we present the first approach to generate branching-pattern aware topologically consistent morphing animation between topologically different leafy trees.Specifically,the proposed method is capable of gener-ating both detail-preserving leaf morphing animations and branch morphing animations si-multaneously,contributing to visually natural and pleasing morphing effects.The core of the proposed method is the automatic and topology-aware segmentation of trees'foliage into canonical geometries,i.e.the lobes,and the branch-pattern aware one-to-many branch cor-respondences.As a result,we seamlessly integrate leaf morphing animations into branch morphing process,which avoids generating“floating”leaves during the morphing process,leading to visually pleasing leafy tree morphing animations.3.Targeting on generating custom stylized special effects for leafy trees,we present a novel sketch-based shape-preserving tree animation method.Users are allowed to interactively draw a 2D view-dependent sketch to define the target tree shape,and the proposed method smoothly transforms the tree into that shape while preserving the morphological meanings of the inbetween trees during the transformation.The core of the proposed method is the self-adaptive cage based hierarchical deformation algorithm.In addition to generating a novel visual effect,the proposed method can also be considered as an intuitive tree editing tool,and demonstrates its potential to leverage existing tree modeling frameworks with flexible and intuitive tree editing operations.