Realistic Modeling of Tree Ramifications from an Optimal Manifold Control Mesh
Modeling realistic branches and ramifications of trees is a challenging task because of their complex geometric structures. Many approaches have been proposed to generate plausible tree models from images, sketches, point clouds, and botanical rules. However, most approaches focus on a global impression of trees, such as the topological structure of branches and arrangement of leaves, without taking continuity of branch ramifications into consideration. To model a complete tree quadrilateral mesh (quad-mesh) with smooth ramifications, we propose an optimization method to calculate a suitable control mesh for Catmull–Clark subdivision. Given a tree’s skeleton information, we build a local coordinate system for each joint node, and orient each node appropriately based on the angle between a parent branch and its child branch. Then, we create the corresponding basic ramification units using a cuboid-like quad-mesh, which is mapped back to the world coordinate. To obtain a suitable manifold initial control mesh as a main mesh, the ramifications are classified into main and additional ramifications, and a bottom-up optimization approach is applied to adjust the positions of the main ramification units when they connect their neighbors. Next, the first round of Catmull–Clark subdivision is applied to the main ramifications. The additional ramifications, which were selected to alleviate visual distortion in the preceding step, are added back to the main mesh using a cut-paste operation. Finally, the second round of Catmull–Clark subdivision is used to generate the final quad-mesh of the entire tree. The results demonstrated that our method generated a realistic tree quad-mesh effectively from different tree skeletons.
KeywordsTree quad-mesh Construction optimization Catmull–Clark subdivision Manifold tree modeling
We thank the ICIG2019 reviewers for their thoughtful comments. The work is supported by the NSFC (61303124), NSBR Plan of Shaanxi (2019JM-370), Key Research and Development Program of Shaanxi (2018NY-127) and the Fundamental Research Funds for the Central Universities (2452017343).
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