Virtual Hand Representations to Support Natural Interaction in Immersive Environment

Immersive Computing Technology (ICT) offers designers the unique ability to evaluate human interaction with product design concepts through the use of stereo viewing and 3D position tracking. These technologies provide designers with opportunities to create virtual simulations for numerous different applications. In order to support the immersive experience of a virtual simulation, it is necessary to employ interaction techniques that are appropriately mapped to specific tasks. Numerous methods for interacting in various virtual applications have been developed which use wands, game controllers, and haptic devices. However, if the intent of the simulation is to gather information on how a person would interact in an environment, more natural interaction paradigms are needed. The use of 3D hand models coupled with position-tracked gloves provide for intuitive interactions in virtual environments. This paper presents several methods of representing a virtual hand model in the virtual environment to support natural interaction

POD for real-time simulation of hyperelastic soft biological tissue using the point collocation method of finite spheres

The point collocation method of finite spheres (PCMFS) is used to model the hyperelastic response of soft biological tissue in real time within the framework of virtual surgery simulation. The proper orthogonal decomposition (POD) model order reduction (MOR) technique was used to achieve reduced-order model of the problem, minimizing computational cost. The PCMFS is a physics-based meshfree numerical technique for real-time simulation of surgical procedures where the approximation functions are applied directly on the strong form of the boundary value problem without the need for integration, increasing computational efficiency. Since computational speed has a significant role in simulation of surgical procedures, the proposed technique was able to model realistic nonlinear behavior of organs in real time. Numerical results are shown to demonstrate the effectiveness of the new methodology through a comparison between full and reduced analyses for several nonlinear problems. It is shown that the proposed technique was able to achieve good agreement with the full model; moreover, the computational and data storage costs were significantly reduced

Virtuality Supports Reality for e-Health Applications

Strictly speaking the word “virtuality” or the expression “virtual reality” refers to an application for things simulated or created by the computer, which not really exist. More and more often such things are becoming equally referred with the adjective “virtual” or “digital” or mentioned with the prefixes “e-” or “cyber-”. So we know, for instance, of virtual or digital or e- or cyber- community, cash, business, greetings, books .. till even pets. The virtuality offers interesting advantages with respect to the “simple” reality, since it can reproduce, augment and even overcome the reality. The reproduction is not intended as it has been so far that a camera films a scenario from a fixed point of view and a player shows it, but today it is possible to reproduce the scene dynamically moving the point of view in practically any directions, and “real” becomes “realistic”. The virtuality can augment the reality in the sense that graphics are pulled out from a television screen (or computer/laptop/palm display) and integrated with the real world environments. In this way useful, and often in somehow essentials, information are added for the user. As an example new apps are now available even for iphone users who can obtain graphical information overlapped on camera played real scene surroundings, so directly reading the height of mountains, names of streets, lined up of satellites .., directly over the real mountains, the real streets, the real sky. But the virtuality can even overcome reality, since it can produce and make visible the hidden or inaccessible or old reality and even provide an alternative not real world. So we can virtually see deeply into the matter till atomic dimensions, realize a virtual tour in a past century or give visibility to hypothetical lands otherwise difficult or impossible to simple describe. These are the fundamental reasons for a naturally growing interest in “producing” virtuality. So here we will discuss about some of the different available methods to “produce” virtuality, in particular pointing out some steps necessary for “crossing” reality “towards” virtuality. But between these two parallel worlds, as the “real” and the “virtual” ones are, interactions can exist and this can lead to some further advantages. We will treat about the “production” and the “interaction” with the aim to focus the attention on how the virtuality can be applied in biomedical fields, since it has been demonstrated that virtual reality can furnish important and relevant benefits in e-health applications. As an example virtual tomography joins together 3D imaging anatomical features from several CT (Computerized axial Tomography) or MRI (Magnetic Resonance Imaging) images overlapped with a computer-generated kinesthetic interface so to obtain a useful tool in diagnosis and healing. With the new endovascular simulation possibilities, a head mounted display superimposes 3D images on the patient’s skin so to furnish a direction for implantable devices inside blood vessels. Among all, we chose to investigate the fields where we believe the virtual applications can furnish the meaningful advantages, i.e. in surgery simulation, in cognitive and neurological rehabilitation, in postural and motor training, in brain computer interface. We will furnish to the reader a necessary partial but at the same time fundamental view on what the virtual reality can do to improve possible medical treatment and so, at the end, resulting a better quality of our life

POD for real-time simulation of hyperelastic soft biological tissue using the point collocation method of finite spheres

The point collocation method of finite spheres (PCMFS) is used to model the hyperelastic response of soft biological tissue in real time within the framework of virtual surgery simulation. The proper orthogonal decomposition (POD) model order reduction (MOR) technique was used to achieve reduced-order model of the problem, minimizing computational cost. The PCMFS is a physics-based meshfree numerical technique for real-time simulation of surgical procedures where the approximation functions are applied directly on the strong form of the boundary value problem without the need for integration, increasing computational efficiency. Since computational speed has a significant role in simulation of surgical procedures, the proposed technique was able to model realistic nonlinear behavior of organs in real time. Numerical results are shown to demonstrate the effectiveness of the new methodology through a comparison between full and reduced analyses for several nonlinear problems. It is shown that the proposed technique was able to achieve good agreement with the full model; moreover, the computational and data storage costs were significantly reduced

Point Primitives Based Virtual Surgery System

In order to achieve a high degree of visual realism in surgery simulation, we present a virtual surgery system framework, which is based on point primitives for the virtual surgery scene rendering and the biomechanical calculation of the soft tissue. To embody the superiority of this framework, two virtual surgery systems based on point primitives we developed are exhibited in this paper. Six critical functional modules were selected as representative of basic and advanced virtual surgery skill. These modules were: 1) point-based texture mapping; 2) deformation simulation; 3) cutting simulation; 4) tearing simulation; 5) dynamic texture mapping; and 6) 3-D display. These modules were elaborated by including working principle, execution process, and the performance of the algorithm. The experimental results have shown that point primitives-based virtual surgery systems obtained higher performance in terms of computational efficiency and rendering effect than traditional meshes-based virtual surgery system

Interactively Cutting and Constraining Vertices in Meshes Using Augmented Matrices

We present a finite-element solution method that is well suited for interactive simulations of cutting meshes in the regime of linear elastic models. Our approach features fast updates to the solution of the stiffness system of equations to account for real-time changes in mesh connectivity and boundary conditions. Updates are accomplished by augmenting the stiffness matrix to keep it consistent with changes to the underlying model, without refactoring the matrix at each step of cutting. The initial stiffness matrix and its Cholesky factors are used to implicitly form and solve a Schur complement system using an iterative solver. As changes accumulate over many simulation timesteps, the augmented solution method slows down due to the size of the augmented matrix. However, by periodically refactoring the stiffness matrix in a concurrent background process, fresh Cholesky factors that incorporate recent model changes can replace the initial factors. This controls the size of the augmented matrices and provides a way to maintain a fast solution rate as the number of changes to a model grows. We exploit sparsity in the stiffness matrix, the right-hand-side vectors and the solution vectors to compute the solutions fast, and show that the time complexity of the update steps is bounded linearly by the size of the Cholesky factor of the initial matrix. Our complexity analysis and experimental results demonstrate that this approach scales well with problem size. Results for cutting and deformation of 3D linear elastic models are reported for meshes representing the brain, eye, and model problems with element counts up to 167,000; these show the potential of this method for real-time interactivity. An application to limbal incisions for surgical correction of astigmatism, for which linear elastic models and small deformations are sufficient, is included