Adaptive Volume Modeling and Rendering for Volume-based Haptic Communication

外科手术训练系统需要用于外科手术任务的实践。在这样的系统中，物体的形状和变形必须快速正确地计算以获得逼真的模拟。通常使用三角形或四面体（其为网格元素）来表示虚拟对象。然而，当网格单元数目增加时，计算时间也增加。此外，当我们需要根据虚拟物体的变形和虚拟手术工具的交互来表示网格时，如果从一开始就重新组装网格，则需要花费大量的时间。这种表示适应于场值的梯度，同时保持其不连续性。在本文中，我们提出了一个四面体自适应表示技术。根据局部场的方向性和方向性等特性，提出了一种四面体自适应网格生成的并行算法， ...更多信息 然后，我们提出了一种四面体自适应网格的在线重构算法。模型，以实现软对象的实时模拟。该算法根据四面体边的拉伸比，对四面体自适应网格进行快速的动态结构修改。该方法首先根据软物体体积的复杂性，对软物体的自适应四面体模型进行局部剖分或简化，然后根据网格结构的任意变形，对四面体进行递归二进制剖分和合并，实现实时在线网格重划。我们已经开发了一种新颖的基于体积的触觉通信系统，该系统基于自适应四面体体积模型的在线重新网格模拟，其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交互，通过仅交换目标对象的一小组操纵参数。我们首先开发了一个在线重新网格体积模型，我们称之为动态自适应网格，用于模拟可变形物体，如软组织在每个远程站点。然后在与目标物体交互过程中的触觉感知，通过渲染来自物体的反射力来实现，从所有远程站点之间交换的操作参数中使用在线重新网格化体模型来模拟。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