Head-worn displays are becoming a viable visual display option for mobile augmented reality. In this paper, we highlight the challenges and some recent progress towards compact and lightweight head-worn displays tending towards the eyeglass form factor. Single and dual-element eyeglass display designs that leverage the advances in free-form optics fabrication technology will be presented. There are three new contributions in this paper: first, we present a single-element eyeglass display design and the fabricated mirror prototype; second, we present our second generation dual-element eyeglass display design with the revised opto-mechanical packaging; third, we present our initial studies on the field of view limit with an 8 mm pupil for the dual-element design.

In this paper, we propose a physics-based and physiology-based approach for modeling real-time deformations of 3-D high-resolution polygonal lung models obtained from high-resolution computed tomography (HRCT) images of normal human subjects. The physics-based deformation operator is nonsymmetric, which accounts for the heterogeneous elastic properties of the lung tissue and spatial-dynamic flow properties of the air. An iterative approach is used to estimate the deformation with the deformation operator initialized based on the regional alveolar expandability, a key physiology-based parameter. The force applied on each surface node is based on the airflow pattern inside the lungs, which is known to be based on the orientation of the human subject. The validation of lung dynamics is done by resimulating the lung deformation and comparing it with HRCT data and computing force applied on each node derived from a 4-D HRCT dataset of a normal human subject using the proposed deformation operator and verifying its gradient with the orientation.

Augmented reality (AR) systems add visual information to the world by using advanced display techniques. The advances in miniaturization and reduced hardware costs make some of these systems feasible for applications in a wide set of fields. We present a potential component of the cyber infrastructure for the operating room of the future: a distributed AR-based software-hardware system that allows real-time visualization of three-dimensional (3-D) lung dynamics superimposed directly on the patient's body. Several emergency events (e.g., closed and tension pneumothorax) and surgical procedures related to lung (e.g., lung transplantation, lung volume reduction surgery, surgical treatment of lung infections, lung cancer surgery) could benefit from the proposed prototype.

Medical simulations of lung dynamics promise to be effective tools for teaching and training clinical and surgical procedures related to lungs. Their effectiveness may be greatly enhanced when visualized in an augmented reality (AR) environment. However, the computational requirements of AR environments limit the availability of the central processing unit (CPU) for the lung dynamics simulation for different breathing conditions. In this paper, we present a method for computing lung deformations in real time by taking advantage of the programmable graphics processing unit (GPU). This will save the CPU time for other AR-associated tasks such as tracking, communication, and interaction management. An approach for the simulations of the three-dimensional (3-D) lung dynamics using Green's formulation in the case of upright position is taken into consideration. We extend this approach to other orientations as well as the subsequent changes in breathing. Specifically, the proposed extension presents a computational optimization and its implementation in a GPU. Results show that the computational requirements for simulating the deformation of a 3-D lung model are significantly reduced for point-based rendering.

In this paper we discuss a framework for modeling the 3D lung dynamics of normal and diseased human subjects and visualizing them using an Augmented Reality (AR) based environment. The framework is based on the results obtained from pulmonary function tests and lung image-data of human subjects obtained from 4D High-Resolution Computed Tomography (HRCT). The components of the framework include a parameterized pressure-volume (PV) relation estimated from normal human subjects, and a physics and physiology-based 3D deformable lung model extracted from the 4D HRCT data of normal and tumor-influenced human subjects. The parameterized PV relation allows modeling different breathing conditions of a human subject. The 3D deformable lung model allows visualizing the 3D shape changes of the lung for the breathing condition simulated by the PV relation. Additionally, the 3D lung model is deformed using a graphics processing unit (GPU) and its vertex shaders, which satisfies the real-time frame-rate requirements of the AR environment.

Provides an abstract for each of the presentations and a brief professional biography of each presenter. The complete presentations were not made available for publication as part of the conference proceedings.

We are proposing an optical see-through head-worn display that is capable of mutual occlusions. Mutual occlusion is an attribute of an augmented reality display where real objects can occlude virtual objects and virtual objects can occlude real objects. For a user to achieve the perception of indifference between the real and the virtual images superimposed on the real environment, mutual occlusion is a strongly desired attribute for certain applications. This paper presents a breakthrough in display hardware from a mobility (i.e. compactness), resolution, and a switching speed based criteria. Specifically, we focus on the research that is related to virtual objects being able to occlude real objects. The core of the system is a spatial light modulator (SLM) and polarization-based optics which allow us to block or pass certain parts of a scene which is viewed through the head-worn display. An objective lens images the scene onto the SLM and the modulated image is mapped back to the original scene via an eyepiece. We are combining computer generated imagery with the modulated version of the scene to form the final image a user would see.

Many tracking systems utilize collections of fiducial markers arranged in rigid configurations, called tracking probes, to determine the pose of objects within an environment. In this paper, we present a technique for designing tracking probes called the viewpoints algorithm. The algorithm is generally applicable to tracking systems that use at least three fiduciary marks to determine the pose of an object. The algorithm is used to create an integrated, head-mounted display tracking probe. The predicted accuracy of this probe was 0.032 /spl plusmn/ 0.02 degrees in orientation and 0.09 /spl plusmn/ 0.07 mm in position. The measured accuracy of the probe was 0.028 /spl plusmn/ 0.01 degrees in orientation and 0.11 /spl plusmn/ 0.01 mm in position. These results translate to a predicted, static positional overlay error of a virtual object presented at 1m of less than 0.5 mm. The algorithm is part of a larger framework for designing tracking probes based upon performance goals and environmental constraints.

Tracking is a necessity for interactive virtual environments. Marker-based tracking solutions involve the placement of fiducials in a rigid configuration on the object(s) to be tracked, called a tracking probe. The realization that tracking performance is linked to probe performance necessitates investigation into the design of tracking probes for proponents of marker-based tracking. A challenge involved with probe design is predicting the accuracy of a tracking probe. We present a method for predicting the accuracy of a tracking probe based upon a first-order propagation of the errors associated with the markers on the probe. Results for two sample tracking probes show excellent agreement between measured and predicted errors.

A real-time physiologically-based breathing model of lungs under normal and pathological scenario has been conceived and implemented. The algorithm developed for lung deformations under various breathing scenarios uses polygonal models of lungs. The method developed avoids the "stiffness" problem observed in mass-spring models. Hardware acceleration of the exhalation and the inhalation process is done using vertex shaders. The method of deformation is general and can be applied to any lung model.

A head-mounted projective display (HMPD) consists of a pair of miniature projection lenses, beam splitters and displays mounted on the helmet and retro-reflective sheeting materials placed strategically in the environment. This has recently been proposed as an alternative to existing 3D visualization devices. In this paper, we first briefly review HMPD technology, including its featured capabilities and the recent development in both display implementations and applications. Then the implementation of a testbed for playing a "Go" game with a remote opponent in a 3D augmented environment is described. The testbed not only demonstrates the capabilities of virtual-real augmentation and registration, the natural occlusion of virtual objects by real ones, interaction with augmented environments and networking collaboration, but also embodies part of our long-term objective to develop a collaborative framework in 3D augmented environments. Through the testbed, major calibration issues, such as accommodation/convergence considerations and determination of viewing transformations, are studied and discussed in detail. Both calibration methods and results are included, which are applicable to other applications. Finally, experimental results of the testbed implementation are presented.

Head-mounted projective displays (HMPD) have been recently proposed as an alternative to conventional eyepiece-type head-mounted displays. HMPDs consist of a pair of miniature projection lenses and displays mounted on the helmet and retro-reflective sheeting materials placed strategically in the environment. Its novel concept and properties suggest solutions to part of the problems of state-of-the-art visualization devices and make it extremely suitable for multiple-user collaborative applications and wearable systems. A brief review of conventional visualization techniques is followed by an extensive discussion of HMPD technology, which includes a summary of its features and a comparison with conventional head-mounted displays (HMDs), projection-based displays, and HMPDs. An ultra-light and compact design (i.e. 8g) of a projection lens system using diffractive optical element (DOE) as well as plastic components for a HMPD is presented. Through the usage of fast prototyping technology, a compact stereoscopic head-mounted prototype with weight less than 700 grams was implemented, and optomechanical adjustments and ergonomic considerations are discussed. Finally, the motivated application in multiuser tele-collaboration is described.