Abstract Displaying 3D geological models and performing corresponding analyses in web browsers are trends in "smart city" development, but these tasks are often limited by the web browser and network transmission; therefore, large quantities of data cannot be quickly displayed or analysed, thereby constraining 3D geological models implemented in web browsers. The data redundancy and computational complexity of 3D geological models must be urgently optimized. Because of the data structure, it is difficult to further optimize the data redundancy and computational complexity of the current commonly used triangular prism (TP) model. If the model is sufficiently large, it can be difficult to display and analyse information in a web browser. Therefore, a new data structure and algorithm are necessary to optimize the data and number of calculations in 3D geological models. Thus, this paper uses a two-dimensional projection to simplify the data and proposes a new data structure for a 3D geological model based on a vertically projected triangulated network (VPTN) to describe the TP model. Based on the vertical sides of a TP, the horizontal coordinates and topology of the 3D model can be recorded by a 2D vertically projected triangulated network. According to the new data structure, this paper proposes a corresponding cutting algorithm that takes advantage of a VPTN to increase the computational speed. The VPTN model and TP model of a city in eastern China are built. The comparison of the modelling and cutting results of the two models is carried out, and the results show that the VPTN model can completely record the spatial coordinate information and topological information of the 3D geological model, reduce the memory space occupied by the model and decrease the number of calculations. The research results meet the needs of rapidly displaying 3D geological models and performing related analyses with a large data volume in web browsers. Moreover, these findings provide a reference for further optimization of 3D geological models.

中文翻译：

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基于垂直投影三角网的三维地质模型及切割算法

摘要 在Web浏览器中显示3D地质模型并进行相应分析是“智慧城市”发展的趋势，但这些任务往往受到Web浏览器和网络传输的限制；因此，无法快速显示或分析大量数据，从而限制了在 Web 浏览器中实现的 3D 地质模型。3D地质模型的数据冗余和计算复杂度亟待优化。由于数据结构的原因，目前常用的三棱柱（TP）模型的数据冗余和计算复杂度难以进一步优化。如果模型足够大，则可能难以在 Web 浏览器中显示和分析信息。所以，需要新的数据结构和算法来优化 3D 地质模型中的数据和计算数量。因此，本文采用二维投影来简化数据，并提出了一种新的数据结构，用于基于垂直投影三角网（VPTN）的 3D 地质模型来描述 TP 模型。基于TP的垂直边，3D模型的水平坐标和拓扑可以通过2D垂直投影三角网记录。根据新的数据结构，本文提出了相应的切割算法，利用VPTN来提高计算速度。建立了华东某城市的VPTN模型和TP模型。对两种模型的建模和切割结果进行了对比，结果表明，VPTN模型能够完整记录3D地质模型的空间坐标信息和拓扑信息，减少模型占用的存储空间，减少计算次数。研究成果满足了在Web浏览器中快速显示3D地质模型和进行大数据量相关分析的需要。此外，这些发现为进一步优化3D地质模型提供了参考。