Zhaoliang Duan

Parallel computing of 3D smoking simulation based on OpenCL heterogeneous platform

Open Computing Language (OpenCL) is an open royalty-free standard for general purpose parallel programming across Central Processing Units (CPUs), Graphic Processing Units (GPUs) and other processors. This paper introduces OpenCL to implement real-time smoking simulation in a virtual surgery training simulation system. Firstly, the Computational Fluid Dynamics (CFD) is adopted to construct the real-time smoking simulation model based on the Navier–Stokes (N-S) equations of an incompressible fluid under the condition of normal temperature and pressure. Then we propose a parallel computing technique based on OpenCL to accomplish the parallel computing of smoking simulation model on CPU and GPU, respectively. Finally, we render the smoke in real time by using a three-dimensional (3D) texture volume rendering method. Experimental results show that the parallel computing technique we have proposed achieve a satisfactory effect on image quality and rendering rate both on CPU and GPU.

3D soft tissue warping dynamics simulation based on force asynchronous diffusion model

Soft tissue warping is one of the key technologies of medical dynamics simulation, such as surgical simulation, image guided surgery. In this paper, we present a novel simulation method which is stable and fast like linear models for soft tissue warping simulation. This method performs on the irregular mesh models, and it is able to represent the visual properties of physical processes with low computational complexity using the Force Asynchronous Diffusion Model (FADM) proposed in this paper. It contains three parts: model preprocessing, collision detection and simulation model solution. In model preprocessing, we establish three models based on the triangular mesh: the geometrical model, the physical model and the transitional model. A two‐level collision detection algorithm is presented based on the three models. At every time step of the simulation model solution, to more accurately reflect the internal physical properties of the soft tissue, we divide the springs in physical model into three kinds: tissue springs, connection springs and virtual springs; and we propose the asynchronous regions and active regions to simplify the computing process according to the realistic physical warping. Experimental results show the FAMD can achieve good warping effects on speed and realism. Copyright

A Robust Physics-Based 3D Soft Tissue Parameters Estimation Method for Warping Dynamics Simulation

Soft tissue warping is one of the key technologies in dynamic simulation of many surgical procedures. To achieve high performance simulation of 3D soft tissue warping, the research of physical parameters estimation of the warping model is of great significance. Through the construction of parameters estimation platform which consists of an optical tracking system PPT2 (Precision Position Tracker with 2 Cameras) and pressure acquisition devices, we obtain the nodal displacements of tetrahedron finite element model and external forces on it. Then we calculate the parameters of 3D soft tissue by using reverse engineering method and verify the parameters by comparing the calculated nodal displacements and the measured nodal displacements of the soft tissue. The experimental results show that the Physics-based 3D soft tissue parameters estimation method we proposed have achieve accurate agreement of calculated nodal displacements and the measured nodal displacements and it has the properties of accuracy and robust;

An energy-based free boundary asynchronous diffusion model for 3D warping of tissue dynamics

Soft tissue warping is one of the key technologies in dynamic simulation of many surgical procedures, such as image-guided surgery, surgical navigation and structural/lesion localization. Previously, we proposed a force asynchronous diffusion model (FADM) for soft tissue warping simulation. The FADM works well if a lesion or an anatomical object has a convex shape. However, in some cases, this convex assumption is invalid. In order to remove this significant limitation, this paper presents an energy-based free boundary asynchronous diffusion model (EBFBADM) with three unique features. First, we utilize hexahedral voxels to represent the physical model of the surface triangular mesh and a regional proliferation algorithm to remove invalid voxels, simplify computation and improve realness in warping simulation. Second, we adopt the concept of free boundary to simulate soft tissue geometric characteristics more precisely during the warping process. Finally, we optimize the process of asynchronous diffusion by using the mechanical energy of mass point to achieve realistic soft tissue warping effects. Experimental results have shown that the EBFBADM improves performance in both computation and realness in surgical simulation.

Real Time Simulation of Tissue Cutting Based on GPU and CUDA for Surgical Training

A novel approach to the simulation of soft tissue cutting in a virtual reality endoscopic simulator is presented for applications in surgical training and education. This approach is based on an improved mass-spring model and the use of computational geometry. A virtual spring is introduced to compensate the weakness of the conventional mass-spring model, and a detection algorithm utilizing decomposition of affine coordinates is adopted to determine the springs that intersect with the cutting plane. In order to achieve real-time computation in the surgical simulation system, algorithms and data structures for the cutting model are implemented on GPU. The simulation performances of the GPU and CPU are compared, and experimental results are described.

Parameter measurement of 3D soft tissue model in warping simulation

Parameter measurement of 3D soft tissue model is of great theoretical significance and application value in virtual surgery training simulation system. To solve the problems of existing soft tissue parameter measurement methods with high complexity, we propose a fast and effective parameter measurement method. We adopt a pillow as test material and exert pressure on it to simulate the parameter measurement of 3D soft tissue model in warping simulation. During the experiment, we construct a motion capture system with 3 cameras to obtain the warping set of the soft tissue model and carry out the 3D reconstruction of it by utilizing reverse engineering method. We obtain the pressure by using a miniature pressure sensor and calibrate the pressure sensor with BP (Back Propagation) neural network and then we calculate the 3D soft tissue parameter by using the pressure data and the 3D reconstruction result. The experimental results show that the parameter measurement method we proposed can obtain the parameter of 3D soft tissue model fast and effectively.

A method for space tracking and positioning of surgical instruments in virtual surgery simulation

As the unique interface for users to communicate with virtual environment, space tracking and positioning apparatus of surgical instruments is an indispensable part of virtual surgery simulation system. A method based on stereoscopic vision is proposed to construct a suit of space tracking and positioning apparatus of surgical instruments. It is able to capture spatial movements of simulated surgical instrument in real time, and provide corresponding six degree of freedom information with the absolute error of less than 1 mm. In order to verify its feasibility, this method is integrated into soft tissue deformation simulation in virtual surgery, and the experimental results show that the developed apparatus is highly accurate, easily operated, and inexpensive.

Research on the key technologies of virtual acupuncture simulation based on JOGL

It is of great significance and application value to train acupuncture learners with modern information technology. We synthetically utilize the technologies of Computer Graphics and Virtual Reality to propose a data optimization method of 3D human body model and make visualization processing of the human body model as well as pick up the human body acupuncture points by using JOGL (Java OpenGL). On Netbeans IDE, we integrate each function model and develop a virtual acupuncture simulation software prototype system which is suitable for the acupuncture learners. Research shows that the key technologies we studied improved the acupuncture simulation programs execution efficiency and enhanced the interactive function in the process of acupuncture training.