| Co-Investigator(Kenkyū-buntansha) |
HIRAI Shinichi Ritsumeikan University, College of Science and Engineerring, Professor (90212167)
SHIMADA Nobutaka Ritsumeikan University, College of information Science and Engineerring, Associate Professor (10294034)
CHEN Yen-Wei Ritsumeikan University, College of information Science and Engineerring, Professor (60236841)
MORIKAWA Shigehiro Shiga University of Medical Science, Biomedical MR Science Center, Associate Professor (60220042)
TANAKA Satoshi Ritsumeikan University, College of information Science and Engineerring, Professor (60251980)
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| Research Abstract |
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
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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
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