Organization model cutting method based on tetrahedron in virtual operation training system

Abstract

The invention relates to an organization model cutting method based on tetrahedrons in a virtual operation training system. The organization model cutting method includes the following steps: picking up a present collision point from a collision detecting system, refining a model and generating a potential cleavage plane through a potential cleavage plane generating module according to the collision point, cutting the model preliminarily through a face cleavage module, detecting whether phenomenon of isolated points exists or not through a point cleavage module, if so, conducting the cleavage on the isolated points, judging whether all nodes after cleavage form a complete tangent plane or not, generating a cutting plane and an outline of the cutting plane according to the cleavage points, conducting lossless Laplace smoothness on nodes of the outline, conducting normal Laplace smoothness on nodes of the cutting plane, conducting intelligent Laplace smoothness on nodes of all tetrahedrons inside the system, and conducting surface exchanging optimization on the internal tetrahedrons. Compared with the prior art, the organization model cutting method based on the tetrahedrons in the virtual operation training system has the advantages of being high in precision and robustness, and capable of imitating organization model cutting efficiency and keeping organization model quality, and the like.

Description

technical field [0001] The invention relates to a method in a virtual surgery system, in particular to a tetrahedron-based tissue model cutting method in a virtual surgery training system. Background technique [0002] The virtual surgery system originated from the medical staff's need for visualization of complex 3D medical data. After a certain period of time, it has developed to the real-time operation of the reconstructed data. One of the typical needs is the reconstructed human tissue such as skin. , blood vessels, organs and other models for cutting. In the virtual surgery system, accurately simulating the cutting effect of the tissue model plays a decisive role in the training of doctors or in estimating the complexity of surgery. The tissue cutting method applied in the virtual surgery system should have sufficient operating efficiency, and the cutting phenomenon should be represented as realistically as possible, and the quality of the model itself should not be se...

AI Technical Summary

Problems solved by technology

In the volume model cutting method proposed by the French National Institute of Information and Automation, all tetrahedral elements that collide with the device are directly deleted. In order to reduce visual defects, the grid is corrected before deletion. Their The work is mainly aimed at efficient cutting methods and maintaining the integrity of the model, that is, eliminating encouraging connection points. However, because this method does not explore much in terms of accuracy, it still has visual defects compared to other methods.

The method proposed by the University of Utrecht in the Netherlands avoids the elimination of tetrahedral elements directly. In their method, according to the result of the collision, the nodes of the model are moved to the cutting trajectory of the instrument, so the segmented model will be Generate a cutting surface that matches the cutting path, but this method does not generate a new tetrahedron, only changes the shape of the existing tetrahedron to conform to the collision result, and does not support multiple cutting and single complex cutting.

The computer graphics laboratory of the Zurich University of Technology in Switzerland proposed a state machine method for tetrahedron model segmentation. They divided the situation of a single tetrahedron during the entire cutting process into 20 states, and performed the state according to the collision between the current tetrahedron unit and the device. In their work, cutting accuracy and time efficiency are the main considerations. In their algorithm, a single tetrahedron unit is divided into 17 smaller tetrahedron units, and their quality cannot be guaranteed. Therefore, on the one hand, it is possible will cause the number of tetrahedrons to rise sharply, the speed will be affected, on the other hand a poor quality model will cause the physics simulation to become unstable

The current method fails to consider the three aspects of speed, accuracy and model quality, and these three aspects have a crucial impact on whether the cutting method can be well applied to the virtual surgery system

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