CPU–GPU mixed implementation of virtual node method for real-time interactive cutting of deformable objects using OpenCL

Abstract

Our cutting algorithm can produce continuous cut surfaces when traditional minimal element creation algorithm fails. Our GPU-accelerated deformation algorithm remains stable with constant time step under multiple arbitrary cuts and works on both NVIDIA and AMD GPUs. GPU-CPU speed ratio can be as high as 10 for models with 80,000 tetrahedrons. Forty to sixty percent real-time performance and 100-200 Hz simulation rate are achieved for the liver model with 3,101 tetrahedrons. Major bottlenecks for simulation efficiency are cutting, collision processing and CPU-GPU data transfer. Future work needs to improve on these areas.

A review of virtual cutting methods and technology in deformable objects

“…Wang et al presented a method that could maintain a well‐shaped mesh and split a tetrahedron into arbitrary pieces; while compared with, it only needs surface representation of the embedded geometry and adds the ability to pass through vertices, the edges and faces of the tetrahedron and have a lower complexity . Jia et al introduced Graphics Processing Unit (GPU) into the virtual node algorithm used in surgery simulation, in which collision and cutting are processed on a Central Processing Unit (CPU), while deformation is processed on a GPU . Although the virtual node algorithm does not create ill‐shaped elements and can process in real time, the virtual node algorithm cannot address partial cuts and simulates physical deformation incorrectly.…”

“…In the literature on cutting simulation of deformable objects, there are several ways to address tetrahedral meshes. These include element deletion, 3 splitting along the existing grid boundary, [15][16][17] node snapping, 2,35 mesh subdivision, [4][5][6][7][8][9][10][11]14,[36][37][38][39] element duplication [40][41][42][43] and a method that combines the above methods. The basic ideas of these methods are expressed in Figure 1.…”

Interactive Cutting of Thin Deformable Objects

“…Tetrahedral meshes were used as simulation meshes in [19][20][21]. The virtual node method proposed in [19] generated a well-shaped tetrahedron for each material branch.…”

“…The virtual node method proposed in [19] generated a well-shaped tetrahedron for each material branch. Although arbitrary cut [20] and Graphics Processing Unit (GPU)-accelerated simulation [21] can be supported by this method, the connectivity analysis of tetrahedrons is not very efficient. In our work, hexahedral meshes are adopted for the simulation, for their regular structures.…”

CPU–GPU Parallel Framework for Real‐Time Interactive Cutting of Adaptive Octree‐Based Deformable Objects

“…This can easily create degenerated or very small elements that decrease the numerical stability of deformation, as stated before. The virtual node method [MBF04, SDF07, WJS*14, JZY*15] embeds cut fragments in virtual elements, the former are used for visual display and collision, while the latter are used for deformation. Virtual elements are duplicates of the original uncut elements.…”