Greg Welch

University of Central Florida | UCF · Institute for Simulation and Training

360-degree experiences such as cinematic virtual reality and 360-degree videos are becoming increasingly popular. In most examples, viewers can freely explore the content by changing their orientation. However, in some cases, this increased freedom may lead to viewers missing important events within such experiences. Thus, a recent research thrust...

In the fields of augmented reality (AR) and virtual reality (VR), many applications involve user interfaces (UIs) to display various types of information to users. Such UIs are an important component that influences user experience and human factors in AR/VR because the users are directly facing and interacting with them to absorb the visualized in...

Due to the additive light model employed by most optical see through head-mounted displays (OST-HMDs), they provide the best augmented reality (AR) views in dark environments, where the added AR light does not have to compete against existing real-world lighting. AR imagery displayed on such devices loses a significant amount of contrast in well-li...

Past work in augmented reality has shown that temperature-associated AR stimuli can induce warming and cooling sensations in the user, and prior work in psychology suggests that a person's body temperature can influence that person's sense of subjective perception of duration. In this paper, we present a user study to evaluate the relationship betw...

Current virtual reality (VR) head-mounted displays (HMDs) are characterized by a low angular resolution that makes it difficult to make out details, leading to reduced legibility of text and increased visual fatigue. Light-on-dark graphics modes, so-called "dark mode'' graphics, are becoming more and more popular over a wide range of display techno...

It is made from wood, projectors, and a computer running multiprojector blending software. Developed in 2008–2009 in response to an agency interest in future work environments for intelligence analysts, the immersive curved ADesk supports a variety of tasks, such as traditional office or development work, design, and even immersive telepresence. Th...

Accurate information about dynamic states is important for efficient control and operation of a power system. This paper compares the performance of four Bayesian-based filtering approaches in estimating dynamic states of a synchronous machine using phasor measurement unit data. The four methods are extended Kalman filter, unscented Kalman filter,...

We present an approach to model dynamic, data-driven source and listener directivity for interactive wave-based sound propagation in virtual environments and computer games. Our directional source representation is expressed as a linear combination of ...

Physical training ranges have been shown to be critical in helping trainees integrate previously-perfected skills. There is a growing need for streamlining the feedback participants receive after training. This need is being met by two related research efforts: approaches for automated camera selection and control, and computer vision-based approac...

The training objective for urban warfare includes acquisition and perfection of a set of diverse skills in support of kinetic and non-kinetic operations. The US Marines (USMC) employ long-duration acted scenarios with verbal training feedback provided sporadically throughout the training session and at the end in a form of an after-action review (A...

This paper describes performance evaluation of a wearable augmented reality system for natural outdoor environments. Applied Research Associates (ARA), as prime integrator on the DARPA ULTRA-Vis (Urban Leader Tactical, Response, Awareness, and Visualization) program, is developing a soldier-worn system to provide intuitive ‘heads-up’ visualization...

The 20th IEEE Virtual Reality Conference (VR 2013) held March 16th - 20th spans five days, with the first two days including five workshops and three tutorials. The following three days includes a strong program of papers, panels, posters, demos, and videos. Of special note is that this year featured both a high number of, and a higher than usual q...

To reduce the computational load of the ensemble Kalman filter while maintaining its efficacy, an optimization algorithm based on the generalized eigenvalue decomposition method is proposed for identifying the most informative measurement subspace. When the number of measurements is large, the proposed algorithm can be used to make an effective tra...

We introduce the notion of Shader Lamps Virtual Patients (SLVP) - the combination of projector-based Shader Lamps Avatars and interactive virtual humans. This paradigm uses Shader Lamps Avatars technology to give a 3D physical presence to conversational virtual humans, improving their social interactivity and enabling them to share the physical spa...

Applications such as telepresence and training involve the display of real or synthetic humans to multiple viewers. When attempting to render the humans with conventional displays, non-verbal cues such as head pose, gaze direction, body posture, and facial expression are difficult to convey correctly to all viewers. In addition, a framed image of a...

Large networks of cameras have been increasingly employed to capture dynamic events for tasks such as surveillance and training. When using active cameras to capture events distributed throughout a large area, human control becomes impractical and unreliable. This has led to the development of automated approaches for on-line camera control. We int...

Applying Kalman filtering techniques to dynamic state estimation is a developing research area in modern power systems. Compared to traditional steady state estimators, the Kalman filter is able to track dynamic state variables both efficiently and accurately. However, in large-scale and wide- area interconnected power systems, the combination of c...

Power system measurement devices continue to evolve towards higher accuracy and update rate. On the other hand, the computation required for processing the enormous amounts of measurement data associated with large complex power systems makes real-time estimation a major challenge. In this paper we present the Lower Dimensional Measurement-space (L...

We introduce a general technique for blending imagery from multiple projectors on a tracked, moving, non-planar object. Our technique continuously computes visibility of pixels over the surfaces of the object and dynamically computes the per-pixel weights for each projector. This approach supports smooth transitions between areas of the object illu...

Two-dimensional (2D) video-based telemedical consultation has been explored widely in the past 15–20 years. Two issues that seem to arise in most relevant case studies are the difficulty associated with obtaining the desired 2D camera views, and poor depth perception. To address these problems we are exploring the use of a small array of cameras to...

Military training conducted on physical ranges that match a unit’s future operational environment provides an invaluable experience. Today, to conduct a training exercise while ensuring a unit’s performance is closely observed, evaluated, and reported on in an After Action Review, the unit requires a number of instructors to accompany the different...

Applications such as telepresence and training involve the display of real or synthetic humans to multiple viewers. When attempting to render the humans with conventional displays, non-verbal cues such as head pose, gaze direction, body posture, and facial expression are difficult to convey correctly to all viewers. In addition, a framed image of a...

Motion segmentation is a fundamental aspect of tracking in a scene with multiple moving objects. In this paper we present a novel approach to clustering individual image pixels associated with different 3D rigid motions. The basic idea is that the change of the intensity of a pixel can be locally approximated as a linear function of the motion of t...

We present a novel calibration framework for multi-projector displays that achieves continuous geometric calibration by estimating and refining the poses of all projectors in an ongoing fashion during actual display use. Our framework provides scalability by operating as a distributed system of "intelligent" projector units: projectors augmented wi...

We describe a new sand table display that combines physical models with computer-generated projection and painting-style interaction. Designed for military training, our sand table has physical models of build- ings, illuminated by multiple projectors adding aerial and synthetic imagery, with additional imagery for lo- cation and movement of person...

We are investigating the potential of 3D telepresence, or televideo, technology to support collaboration among geographically separated medical personnel in trauma emergency care situations. 3D telepresence technology has the potential to provide richer visual information than current 2D video conferencing techniques. This may be of benefit in diag...

We conducted an experiment with a posttest, between-subjects design to evaluate the potential of emerging 3D telepresence technology to support collaboration in emergency health care. 3D telepresence technology has the potential to provide richer visual information than do current 2D video conferencing techniques. This may be of benefit in diagnosi...

We present a stochastic state-space quality metric for use in controlling active camera networks aimed at 3D vision tasks such as surveillance, motion tracking, and 3D shape/appearance reconstruction. Specifically, the metric provides an estimate of the aggregate steady-state uncertainty of the 3D resolution of the objects of interest, as a functio...

The paper presents a system for automatic, geo-registered, real-time 3D reconstruction from video of urban scenes. The system collects video streams, as well as GPS and inertia measurements in order to place the reconstructed models in geo-registered coordinates. It is designed using current state of the art real-time modules for all processing ste...

Two-dimensional (2D) video-based telemedical consultation has been explored widely in the past 15–20 years. Two issues that seem to arise in most relevant case studies are the difficulty associated with obtaining the desired 2D camera views, and poor depth perception. To address these problems we are exploring the use of a small array of cameras to...

Emergency trauma is a major health problem worldwide. To evaluate the potential of emerging 3D telepresence technology for facilitating paramedic - physician collaboration while providing emergency medical trauma care we conducted a between-subjects post-test experimental lab study. During a simulated emergency situation 60 paramedics diagnosed and...

The appearance of a scene is a function of the scene contents, the lighting, and the camera pose. A set of n-pixel images of a non-degenerate scene captured from different perspectives lie on a 6D nonlinear manifold in Rⁿ. In general, this nonlinear manifold is complicated and numerous samples are required to learn it globally. In this p...

We report here on applying a complementary tracking and two-handed interaction paradigm to remote medical consultation using a mobile hand-held device. The basic idea is to track the relative pose between the mobile device and an integrated but detachable "patient surrogate" such as the device cover, enabling 6 DOF visu-alization of streaming visio...

Many human motion tracking systems average, integrate, or corre-late device samples over some non-zero period of time in order to produce a single system-level measurement. This is done to reduce the effects of device noise, or because one has no choice with some devices. The problem is that the target (user) is likely to be mov-ing throughout the...

We are investigating the potential of 3D telepresence technology to support collaboration among geographically separated medical personnel in trauma emergency care situations. 3D telepresence technology has the potential to provide richer visual information than current 2D video conferencing techniques. This may be of benefit in diagnosing and trea...

A common approach to model-based tracking is to use a model of the object to predict what will be observed, and then to compare that with real observations. For meth- ods that make use of the object's photometric properties (appearance) in their measurements, illumination inconsi s- tencies between the modeled and actual scene can cause tracking pr...

We describe an interactive software simulator that assists with the design of multi-camera setups for applications such as image-based virtual reality, three-dimensional reconstruction from still or video imagery, surveillance, etc. Instead of automating the camera placement process, our goal is to assist a user by means of a simulator that support...

In 1960, R.E. Kalman published his famous paper describing a recursive solution to the discrete-data linear filtering problem. Since that time, due in large part to advances in digital computing, the Kalman filter has been the subject of extensive research and application, particularly in the area of autonomous or assisted navigation. The Kalman f...

Immersive electronic books (IEBooks) for surgical training will let surgeons explore previous surgical procedures in 3D. The authors describe the techniques and tools for creating a preliminary IEBook, embodying some of the basic concepts.

Most multi-camera vision applications assume a single common color response for all cameras. However different cameras - even of the same type - can exhibit radically different color responses, and the differences can cause significant errors in scene interpretation. To address this problem we have developed a robust system aimed at inter-camera co...

For over a decade we have been pursuing a vision of three- dimensional (3D) telepresence. Our primary driving prob- lem is 3D medical consultation. Our basic goal is to en- hance and expand medical diagnosis and treatment for life- critical trauma scenarios by providing an advising health care provider and a distant medical advisee a "live" high- f...

We present an overview of multi-year efforts aimed at developing technology to support natural telepresence over time for off-line surgical training, and over space for on-line or "live" remote consultation. Our goal is to capture and display high-fidelity, 3D graphical reconstructions of the ac-tual time-varying events, allowing observers to chang...

We present a new method for using commodity graphics hardware to achieve real-time, on-line, 2D view synthesis or 3D depth estimation from two or more calibrated cameras. Our method combines a 3D plane-sweeping approach with 2D multi-resolution color consistency tests. We project camera imagery onto each plane, compute measures of color consistency...

We introduce and present preliminary results for a hybrid display system combining head-mounted and projector-based displays. Our work is motivated by a surgical training application where it is necessary to simultaneously provide both a highfidelity view of a central close-up task (the surgery) and visual awareness of objects and events in the sur...

We introduce and present preliminary results for a hybrid display system combining head-mounted and projector-based displays. Our work is motivated by a surgical training application, where it is necessary to simultaneously provide both a high-fidelity view of a central close-up task (the surgery) and visual awareness of objects and events in the s...

We present a novel use of commodity graphics hardware to perform real-time image segmentation and image morphology operations. Our preliminary results show a performance increase of over 30% using an nVidia GeForce4 when compared to an implementation using Intel MMX optimized code on a 2.2 Ghz Intel P4 CPU.

We describe a new paradigm for three-dimensional computer graphics, using projectors to graphically animate physical objects in the real world. The idea is to replace a physical object---with its inherent color, texture, and material properties---with a neutral object and projected imagery, reproducing the original (or alternative) appearance direc...

This paper reports on early progress with the use of immersive virtual reality technology for trauma surgery training. We discu ss our technical goals and the application area, and then describe our work to date. The need to create a system that can be used by overworked, highly time-constrained surgeons and surgical trainees has affected many of o...

Since the early 1980s, the Tracker Project at the University of North Carolina at Chapel Hill has been working on wide-area head tracking for virtual and augmented environments. Our long-term goal has been to achieve the high performance required for accurate visual simulation throughout our entire laboratory, beyond into the hallways, and eventual...

We present a novel use of commodity graphics hardware that effectively combines a plane-sweeping algorithm with view synthesis for real-time, on-line 3D scene acquisition and view synthesis. Using real-time imagery from a few calibrated cameras, our method can generate new images from nearby viewpoints, estimate a dense depth map from the current v...

We present a novel use of commodity graphics hardware that effectively combines a plane-sweeping algorithm [Collins 1996] and view synthesis in a single step for real-time, on-line 3D view synthesis. Unlike typical stereo algorithms that use image-based metrics to estimate depths, we focus on using image-based metrics to directly estimate images. U...

We introduce an idea and some preliminary results for a new projector-based approach to re-creating real and imagined sites. Our goal is to achieve re-creations that are both visually and spatially realistic, providing a small number of relatively unencumbered users with a strong sense of immersion as they jointly walk around the virtual site. Rath...

this paper, we have mainly focussed on the visualization aspect, but a more detailed study of human interaction and issues is necessary

We describe a new paradigm for three-dimensional computer graphics, using projectors to graphically animate physical objects in the real world. The idea is to replace a physical object---with its inherent color, texture, and material properties---with a neutral object and projected imagery, reproducing the original (or alternative) appearance direc...

Despite the availability of high-quality graphics systems, architects and designers still build scaled physical models of buildings and products. These physical models have many advantages, however they are typically static in structure and surface characteristics. They are inherently lifeless. In contrast, high-quality graphics systems are tremend...

We describe an efficient approach to rendering a perspectively correct image on a potentially irregular display surface that may be illuminated with one or more distinct devices. The first pass of the technique generates an image of the desired graphics model using conventional rendering. The second pass projects that image as a texture onto a mode...