实景三维模型在铁路工程勘察设计方面应用愈发广泛,但在模型可视化过程中的失真现象和纹理贴图被倾斜摄影测量外业环境限制问题较为突出,严重制约实景三维模型的实际效果和应用范围.通过将实景三维模型从常用OSGB格式转化为便于编辑的OBJ格式,并在其数据框架内新建PBR(Physically Based Rendering)材质,以提升模型整体的真实度,最终在OSG(Open Scene Graph)内完成可视化渲染;过程中提出融合实拍照片优化PBR材质的参数设定和按地物材质特性分类的方法来进一步提升实景三维模型的纹理效果;分析OSG引擎内光照模型,选择最匹配铁路工程实际情况和当天作业条件的光照模型应用,在不改变已有数据结构的基础上,突破倾斜摄影作业环境对实景三维模型最终可视化成果质量的桎梏.该方法在既有铁路工程不同部位的实景三维模型上进行验证,结果表明,该技术可有效提升实景三维模型的可视化效果及表达真实度,具备一定的推广应用价值.
Research and Application of PBR Material in Railway Engineering Realistic 3D Model
The application of realistic 3D models in railway engineering survey and design is becoming increasingly widespread,but the distortion phenomenon and texture mapping in the model visualization process are more prominent due to the limitations of oblique photogrammetry field environment,which seriously restricts the actual effect and application scope of realistic 3D models.By converting the real-world 3D model from the commonly used OSGB format to an easily editable OBJ format,and creating a new PBR(Physically Based Rendering)material within its data framework,the overall realism of the model is improved.Finally,visualization rendering is completed within OSG(Open Scene Graph).During the process,a method was proposed to optimize the parameter settings of PBR materials by integrating real-life photos and classifying them according to the characteristics of ground objects to further improve the texture effect of the real scene 3D model.The lighting model within the OSG engine was analyzed,the lighting model application was selected to match the actual situation of railway engineering and the working conditions of the day,and the constraints of the oblique photography working environment on the quality of the final visualization results of the real scene 3D model was overcame without changing the existing data structure.The method has been validated on real-life 3D models of different parts of existing railway engineering,and the results show that the technology can effectively improve the visualization effect and expression realism of real-life 3D models,and has a certain promotion and application value.
railway engineeringrealistic 3D modelPBR materiallighting modelfeature attributes
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