Virtual Objects as Spatial Cues in Collaborative Mixed Reality Environments

Collaboration and guidance are key aspects of many software tasks. In traditional desktop software, such aspects are well supported through built-in collaboration functions or general-purpose techniques such as screen and video sharing. In Mixed Reality environments, where users carry out actions in a three-dimensional space, collaboration and guidance may also be required. However, other users may or may not be using the same Mixed Reality interface. Users may not have access to the same information, the same visual representation, or the same interaction affordances. These asymmetries make communication and collaboration between users harder. To address asymmetries in Mixed Reality environments, we introduce Interactive Mixed-Dimensional Media. In these media, the visual representation of information streams can be changed between 2D and 3D. Different representations can be chosen automatically, based on context, or through associated interaction techniques that give users control over exploring spatial, temporal, and dimensional levels of detail. This ensures that any information or interaction makes sense across different dimensions, interfaces and spaces. We have deployed these techniques in three different contexts: mixed-reality telepresence for physical task instruction, video-based instruction for VR tasks, and live interaction between a VR user and a non-VR user. From these works, we show that Mixed Reality environments that provide users with interactive mixed-dimensional media interfaces improve performance and user experience in collaboration and guidance tasks.

Augmented Reality and Mixed Reality technologies make us feel the real world and the virtual world are mixed with each other through visual matching. However, existing mixed reality contents using these technologies have a limitation that interact only with virtual objects and cannot interact with real objects. If a dynamic real object need to be influenced by a virtual object, or vice versa, illusion of Mixed Reality can be broken by the incongruity of the interaction. If these limitations are improved, real objects, which were always static, can operate dynamically and interact with virtual objects, so becomes difficult to distinguish between real objects and virtual objects. In this paper, we propose extended interactions in a mixed reality environment that can give illusion which is difficult to distinguish between real objects and virtual objects. And to confirm this, we implement authoring environment based Hololens.

The ability to interact with virtual objects using gestures would allow users to improve their experience in Mixed Reality (MR) environments, especially when they use AR headsets. Today, MR head-mounted displays like the HoloLens integrate hand gesture based interaction allowing users to take actions in MR environments. However, the proposed interactions remain limited. In this paper, we propose to combine a Leap Motion Controller (LMC) with a HoloLens in order to improve gesture interaction with virtual objects. Two main issues are presented: an interactive calibration procedure for the coupled HoloLens-LMC device and an intuitive hand-based interaction approach using LMC data in the HoloLens environment. A set of first experiments was carried out to evaluate the accuracy and the usability of the proposed approach.

Virtual reality (VR) technology has become a growing force in entertainment, education, science, and manufacturing due to the capability of providing users with immersive experiences and natural interaction. Although common input devices such as controllers, gamepads, and trackpads have been integrated into mainstream VR systems for user-content interaction, they cannot provide users with realistic haptic feedback. Some prior work tracks and maps the physical objects into the virtual space to allow users to interact with these objects directly, which improves users’ sense of reality in the virtual environment. However, most of them use additional hardware sensors, which inevitably increases the cost. In this research, a lightweight approach is proposed to synchronize the positions and motions between physical and digital objects without any extra costs. We use the real-time captured video data from in-built cameras on a VR headset and employ feature points based algorithms to generate projections of the physical objects in the virtual world. Our approach does not rely on additional sensors but just uses components available in a VR headset. Our approach allows users to interact with target objects with their hands directly without the need for specially designed trackers, markers, and other hardware devices as used in previous work. With our approach, users can get more realistic operational feedback when interacting with corresponding virtual objects.

We seek to design an AR interface that provides users with interactivity so rich it would merge the physical space in which we live and work with the virtual space in which we store and interact with digital information. In this single augmented space, computer-generated entities would become first-class citizens of the physical environment. We would use these entities just as we use physical objects, selecting and manipulating them with our hands instead of with a special-purpose device such as a mouse or joystick. Interaction would then be intuitive and seamless because we would use the same tools to work with digital and real objects. Tiles is an AR interface that moves one step closer to this vision. It allows effective spatial composition, layout, and arrangement of digital objects in the physical environment. The system facilitates seamless two-handed, three-dimensional interaction with both virtual and physical objects, without requiring any special-purpose input devices.

A mixed reality environment for collaborative product design and development

Outdoor rendering is an attractive topic in computer graphics. In this paper our main concern is to reveal the interaction between sky color and virtual objects in Mixed Reality environments. Although registration and tracking are two of the main issues in building effective Augmented Reality (AR) systems the creation of more realistic virtual objects indistinguishable from their real-world counterparts is our target which is currently the ultimate goal in AR. Two classes of sky color generation are employed to reveal the outdoor-element interaction. Virtual Sky Modelling (VSM) based on the Perez Model is capable of generating the sky color in a specific location, date and time. The second technique is to generate a virtual model based on the real image of the sky which is called in this paper Real Sky Modelling (RSM). Subsequently, preprocessing of the sky color bleeding is based on the radiosity technique to give the sky color effect to the virtual objects as well as the real ones. Through designing a test AR set-up and applying software and hardware the goal of a robust generation of realistic virtual objects with effect of sky color is achieved.

The paper describes a collaborative Mixed-Reality (MR) environment to support the product design assessment. In particular, we have developed a collaborative platform that enables us to improve the design and the evaluation of cars interior. The platform consists of two different systems: the 3D Haptic Modeler (3DHM) and the Mixed Reality Seating Buck (MRSB). The 3DHM is a workbench that allows us to modify the 3D model of a car dashboard by using a haptic device, while the MRSB is a configurable structure that enables us to simulate different driving seats. The two systems allow the collaboration among designers, engineers and end users in order to get, as final result, a concept design of the product that satisfies both design constraints and end users’ preferences. The usability of our collaborative MR environment has been evaluated by means of some testing sessions, based on two different case studies, with the involvement of users.

Mixed prototyping is an industrial practice that combines virtual and real components in order to realize a prototype of a product used to evaluate and assess the design choices. Recently, mixed prototypes have been also used to assess the usability of products interface. This particular application arises several problems related to the devices and the interaction techniques that, better than others, allow a natural interaction with the mixed prototype. This paper presents a mixed reality environment for usability evaluation that deals with two specific problems of this kind of application: the occlusion between real and virtual objects and the interpretation of the user’s gestures while he/she is interacting with the elements of the product interface. In particular we propose a technique able to manage both the problems by using only commodity hardware and video processing algorithms, thus avoiding the use of expensive data-gloves and tracking devices. The proposed approach has been validated through a user study addressed to establish whether and to what extent the augmented reality devices and the techniques proposed may distort the usability assessment of the product. Moreover, the user study compares the mixed reality environment adopted in this study with a classical virtual reality set-up.

The problem of robotic and virtual interaction with physical objects has been the subject of research for many years in both the robotic manipulation and haptics communities. Both communities have focused much attention on human touch-based perception and manipulation, modelling contact between real or virtual hands and objects, or mechanism design. However, as a whole, these problems have not yet been addressed from a unified perspective. This edited book is the outcome of a well-attended workshop which brought together leading scholars from various branches of the robotics, virtual-reality, and human studies communities during the 2004 IEEE International Conference on Robotics and Automation. It covers some of the most challenging problems on the forefront of todays research on physical interaction with real and virtual objects, with special emphasis on modelling contacts between objects, grasp planning algorithms, haptic perception, and advanced design of hands, devices and interfaces.

Although gesture-based input and augmented reality (AR) facilitate intuitive human-robot interactions (HRI), prior implementations have relied on research-grade hardware and software. This paper explores using tablets to render mixed-reality visual environments that support human-robot collaboration for object manipulation. A mobile interface is created on a tablet by integrating real-time vision, 3D graphics, touchscreen interaction, and wireless communication. This mobile interface augments a live video of physical objects in a robot's workspace with corresponding virtual objects that can be manipulated by a user to intuitively command the robot to manipulate the physical objects. By generating the mixed-reality environment on an exocentric view provided by the tablet camera, the interface establishes a common frame of reference for the user and the robot to effectively communicate spatial information for object manipulation. After addressing challenges due to limitations in mobile sensing and computation, the interface is evaluated with participants to examine the performance and user experience with the suggested approach.

Developing a vehicle is always a long and complex task. This is especially true for autonomous cars. Tasks performed by the driver are taken over by the vehicle and must be performed with maximum reliability. Developing these systems is a difficult task, especially due to limited testing capabilities. Testing a vehicle in a closed environment is safe and controlled, but the variety of test scenarios is limited. By using mixed reality environments, one can create a diverse environment around a real test vehicle, with traffic, obstacles, and unexpected situations. The real movement of the test vehicle allows testing decision and motion planning level vehicular functions. Information from the virtual world can be considered as input to the vehicle sensor. Mixed reality or digital twin simulation environments can greatly assist the autonomous vehicle development process and also serve as a basis for validation procedures for such systems. This article introduces a mixed reality simulation environment that integrates a real test vehicle into a virtual environment, can handle other real and virtual obstacles, contains traffic simulations, and visualizes all of these.

Visual coherence between real and virtual objects is important in mixed reality (MR), and illumination consistency is one of the key aspects to achieve coherence. Apart from matching the illumination of the virtual objects with the real environments, the change of illumination on the real scenes produced by the inserted virtual objects should also be considered but is difficult to compute in real-time due to the heavy computation demands of global illumination. In this work, we propose delta path tracing (DPT), which only computes the radiance blocked by the virtual objects from the light sources at the primary hit points of Monte Carlo path tracing, then combines the blocked radiance and multi-bounce indirect illumination with the image of the real scene. Multiple importance sampling (MIS) between BRDF and environment map is performed to handle all-frequency environment maps captured by a panorama camera. Compared to conventional differential rendering methods, our method can remarkably reduce the number of times required to access the environment map and avoid rendering scenes twice. Therefore, the performance can be significantly improved. We implement our method using hardware-accelerated ray tracing on modern GPUs, and the results demonstrate that our method can render global illumination at real-time frame rates and produce plausible visual coherence between real and virtual objects in MR environments.

We present a novel adaptive color mapping method for virtual objects in mixed-reality environments. In several mixed-reality applications, added virtual objects should be visually indistinguishable from real objects. Recent mixed-reality methods use global-illumination algorithms to approach this goal. However, simulating the light distribution is not enough for visually plausible images. Since the observing camera has its very own transfer function from real-world radiance values to RGB colors, virtual objects look artificial just because their rendered colors do not match with those of the camera. Our approach combines an on-line camera characterization method with a heuristic to map colors of virtual objects to colors as they would be seen by the observing camera. Previous tone-mapping functions were not designed for use in mixed-reality systems and thus did not take the camera-specific behavior into account. In contrast, our method takes the camera into account and thus can also handle changes of its parameters during runtime. The results show that virtual objects look visually more plausible than by just applying tone-mapping operators.

Throughout optics and photonics, phase is normally controlled via an optical path difference. Although much less common, an alternative means for phase control exists: a geometric phase (GP) shift occurring when a light wave is transformed through one parameter space, e.g., polarization, in such a way as to create a change in a second parameter, e.g., phase. In thin films and surfaces where only the GP varies spatially—which may be called GP holograms (GPHs)—the phase profile of nearly any (physical or virtual) object can in principle be embodied as an inhomogeneous anisotropy manifesting exceptional diffraction and polarization behavior. Pure GP elements have had poor efficiency and utility up to now, except in isolated cases, due to the lack of fabrication techniques producing elements with an arbitrary spatially varying GP shift at visible and near-infrared wavelengths. Here, we describe two methods to create high-fidelity GPHs, one interferometric and another direct-write, capable of recording the wavefront of nearly any physical or virtual object. We employ photoaligned liquid crystals to record the patterns as an inhomogeneous optical axis profile in thin films with a few μm thickness. We report on eight representative examples, including a GP lens with F/2.3 (at 633 nm) and 99% diffraction efficiency across visible wavelengths, and several GP vortex phase plates with excellent modal purity and remarkably small central defect size (e.g., 0.7 and 7 μm for topological charges of 1 and 8, respectively). We also report on a GP Fourier hologram, a fan-out grid with dozens of far-field spots, and an elaborate phase profile, which showed excellent fidelity and very low leakage wave transmittance and haze. Together, these techniques are the first practical bases for arbitrary GPHs with essentially no loss, high phase gradients (∼rad/μm), novel polarization functionality, and broadband behavior.