Research On Understanding, Optimization And Editing Of Model For Visual Computation

In modern automotive styling design, it is not only to meet the technical requirements of manufacturing, but also to meet the personalized needs of users. It is a balance of a variety of feature constraints. In the actual engineering, each stage of the automotive styling design is the loop iteration process of CAD parametric modeling and CAE numerical calculation. That CAD model reflect the design intent precisely, CAE model maintain geometric model feature with high quality mesh is of great significant for design efficiency. Designer are concerned about different constraint features in different stage, taking all constraints into consideration in every styling design stage will enhance the design complexity greatly. Therefore, the study of the impact of the automotive styling features on the overall modeling, and the establishment of the hierarchical structure of automotive styling features is great significant to reduce the design difficulty and improve the design efficiency.Aimed at above problems, we proposed a heterogeneous model understanding method based on hierarchical structure, as well as the parametric surface reconstruction and remeshing method. Extensively we realized the surface deformation driven by hierarchical structure. The research work of this paper is mainly focused on the following aspects:(1) Heterogeneous model understanding based on hierarchical structure. Based on the morphological analysis of plant leaves in nature, we propose a model understanding method based on hierarchical structure. And applying this method to automotive styling feature curves, automotive body styling feature curves hierarchical structure is obtained.(2) Parametric surface reconstruction constrained by hierarchical structure. Its core could be described as:reconstruct parametric surface through the boundary feature of the lowest level, and the surface is aligned to other curves according to its level. In this way, the surface could be rapidly reconstructed according to different accuracy requirements.(3) Remeshing method constrained by hierarchical structure. A sampling strategy is defined, which means hierarchical structure take precedence and auxiliary surface take a subsidiary function, hierarchical structure sampling priority is also determined by the level of feature curves. Finally, the triangle mesh is obtained by CDT triangulation.(4) Automotive body mesh surface deformation. Achieved a discrete mesh deformation method which is driven by continuous geometric curves. Geometric curves and mesh is connected by the resampling process. The fairing deformation of the surface is realized by the least square method.According to the result of the numerical experiments, hierarchical structure parametric constrained surface reconstruction method reduced the blending between surfaces, improving the fairness of surface; hierarchical structure constraint remeshing method could maintain geometric relevant features in multi-scale mesh with high quality mesh; hierarchical structure driven mesh surface deformation achieved surface deformation, which is driven by parametric curves, which means the direct edit to CAE model without CAD parametric surface.