Adaptive Volume Modeling and Rendering for Volume-based Haptic Communication

外科训练系统是外科任务实践所必需的。在这样的系统中，必须快速准确地计算出物体的形状和变形，才能得到真实的仿真结果。通常使用三角形或四面体作为网格元素来表示虚拟对象。然而，随着网格单元数量的增加，计算时间也会增加。此外，当我们想要根据虚拟物体的变形和虚拟手术工具的相互作用来表示网格时，如果从一开始就重新组装网格，我们需要花费很多时间。本工作的第一个目标是构建输入体数据的多分辨率四面体表示。这种表示法在保持场值不连续的同时适应了场值的梯度。本文提出了一种四面体自适应表示技术。我们已经开发了一种四面体自适应网格生成的并行算法，根据局部场属性，如方向和c…等曲面的更多的不确定性，直到整个体积在指定的水平内被近似。其次，我们开发了四面体自适应网格的在线重划分算法。模型，以实现对软对象的实时仿真。它可以根据四面体边缘的拉伸比对四面体自适应网格进行快速动态结构修改。我们通过输入一个适应软物体体积复杂性的自适应四面体体积模型，然后在在线时响应网格结构的任意变形，对四面体进行递归二值分裂和合并，从而局部划分或简化网格以实现实时在线重划分。最后，我们开发了一种基于自适应四面体体积模型的在线网格模拟的新型基于体积的触觉通信系统，该系统允许网络上远程站点的参与者同时与虚拟环境中的相同目标对象进行交互，只需交换目标对象的一小组操作参数。我们首先开发了一个在线网格体积模型，我们称之为动态自适应网格，用于模拟每个远程站点的可变形物体，如软组织。然后，在与目标物体交互过程中，通过渲染物体的反射力来实现触觉感受，并利用各远程位置之间交换的操作参数进行在线网格体模型模拟。少

Surgical training systems are needed for practices of surgical tasks. In such systems, shapes and deformations of objects must be fast calculated correctly to get realistic simulations. Generally triangles or tetrahedra, which are mesh elements, are used to represent virtual objects. However, when the number of mesh elements increase, the calculation time also increase. Moreover, we need much time if meshes are reassembled from the beginning, when we want to represent meshes according to deformations of virtual objects and interraction of virtual surgical tools.The first objective of this work is to construct a multi resolution tetrahedral representation of input volume data. This representation adapts to gradient of field values while preserving their discontinuities. In this paper, we present a tetrahedral adaptive representation technique. We have developed a parallel algorithm of tetrahedral adaptive mesh generation, according to local field properties such as the orientation and c … More urvature of iso-surfaces, until the entire volume has been approximated within a specified level.Next, we have developed the algorithm for online remeshing of tetrahedral adaptive mesh. model, to enable real-time simulation of a soft object. It allows fast dynamic structural modifications of tetrahedral adaptive mesh, according to stretch ration of edges of tetrahedra. We divide or simplify a mesh locally to implement real-time online remeshing by inputting an adaptive tetrahedral volumetric model of a soft object that has been adapted in response to the complexity of the volume of the soft object, then subjecting the tetrahedra to recursive binary splitting and merging in response to an arbitrary deformation of the mesh structure while online.Finally, we have developed a novel volume-based haptic communication system, based on online remesh simulation of adaptive tetrahedral volume model, which allows participants at remote, sites on the network to simultaneously interact with the same target object in virtual environments, by only exchanging a small set of manipulation parameters for the target object. We first developed an online-remesh volume model, we call dynamic adaptive grids, for simulating deformable objects such as soft tissues in each remote site. Then haptic sensation during interaction with the target object, is achieved by rendering the reflection force from the object, simulated with the online-remesh volume model from the manipulation parameters exchanged among all remote sites. Less