This survey summarizes almost 50 years of research and development in the field of Augmented Reality AR. From early research in the1960's until widespread availability by the 2010's there has been steady progress towards the goal of being able to seamlessly combine real and virtual worlds. We provide an overview of the common definitions of AR, and show how AR fits into taxonomies of other related technologies. A history of important milestones in Augmented Reality is followed by sections on the key enabling technologies of tracking, display and input devices. We also review design guidelines and provide some examples of successful AR applications. Finally, we conclude with a summary of directions for future work and a review of some of the areas that are currently being researched.

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A Survey of Augmented Reality

In this paper, we suggest a variational model for optic flow computation based on non-linearised and higher order constancy assumptions. Besides the common grey value constancy assumption, also gradient constancy, as well as the constancy of the Hessian and the Laplacian are proposed. Since the model strictly refrains from a linearisation of these assumptions, it is also capable to deal with large displacements. For the minimisation of the rather complex energy functional, we present an efficient numerical scheme employing two nested fixed point iterations. Following a coarse-to-fine strategy it turns out that there is a theoretical foundation of so-called warping techniques hitherto justified only on an experimental basis. Since our algorithm consists of the integration of various concepts, ranging from different constancy assumptions to numerical implementation issues, a detailed account of the effect of each of these concepts is included in the experimental section. The superior performance of the proposed method shows up by significantly smaller estimation errors when compared to previous techniques. Further experiments also confirm excellent robustness under noise and insensitivity to parameter variations.

Highly accurate optic flow computation with theoretically justified warping

Deep learning has recently gained popularity achieving state-of-the-art performance in tasks involving text, sound, or image processing. Due to its outstanding performance, there have been efforts to apply it in more challenging scenarios, for example, 3D data processing. This article surveys methods applying deep learning on 3D data and provides a classification based on how they exploit them. From the results of the examined works, we conclude that systems employing 2D views of 3D data typically surpass voxel-based (3D) deep models, which however, can perform better with more layers and severe data augmentation. Therefore, larger-scale datasets and increased resolutions are required.

Deep Learning Advances in Computer Vision with 3D Data: A Survey

The tools include components which are images produced by the system (103) that creates the virtual environment in response to inputs specifying the tool's location and the point of view of the tool's user. One class of the tools includes transparent components (121, 123); the image component of the tool is produced at a location in the virtual environment determined by the transparent component's location and the point of view of the tool's user. Tools in this class include a transparent pad (121) and a transparent stylus (123). The transparent pad (121) has an image component that may be used as a palette, as a magic lens, and as a device for selecting and transporting components of the virtual environment or even a portion of the virtual environment itself.

Tools for interacting with virtual environments

We have created and tested Tahuti, a dual-view sketch recognition environment for class diagrams in UML. The system is based on a multi-layer recognition framework which recognizes multi-stroke objects by their geometrical properties allowing users the freedom to draw naturally as they would on paper rather than requiring the user to draw the objects in a pre-defined manner. Users can draw and edit while viewing either their original strokes or the interpreted version of their strokes engendering user-autonomy in sketching. The experiments showed that users preferred Tahuti to a paint program and to Rational Rose™ because it combined the ease of drawing found in a paint program with the ease of editing available in a UML editor.

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Tahuti: a geometrical sketch recognition system for UML class diagrams

A multi-layered architecture for sketch-based interaction within virtual environments

. The advent of technology in digital cameras and their incorporation into virtually any smart mobile device has led to an explosion of the number of photographs taken every day. Today, the number of images stored online and available freely has reached unprecedented levels. It is estimated that in 2011, there were over 100 billion photographs stored in just one of the major social media sites. This number is growing exponentially. Moreover, advances in the fields of Photogrammetry and Computer Vision have led to significant breakthroughs such as the Structure from Motion algorithm which creates 3D models of objects using their twodimensional photographs. The existence of powerful and affordable computational machinery not only the reconstruction of complex structures but also entire cities. This paper illustrates an overview of our methodology for producing 3D models of Cultural Heritage structures such as monuments and artefacts from 2D data (pictures, video), available on Internet repositories, social media, Google Maps, Bing, etc. We also present new approaches to semantic enrichment of the end results and their subsequent export to Europeana, the European digital library, for integrated, interactive 3D visualisation within regular web browsers using WebGl and X3D. Our main goal is to enable historians, architects, archaeologists, urban planners and affiliated professionals to reconstruct views of historical structures from millions of images floating around the web and interact with them.

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Online 4d reconstruction using multi-images available under open access

Virtual assembly training systems show a high potential to complement or even replace physical setups for training of assembly processes in and beyond the automotive industry. The precondition for the breakthrough of virtual training is that it overcomes the problems of former approaches. The paper presents the design approach taken during the development of a game-based, virtual training system for procedural assembly knowledge in the EU-FP7 project VISTRA. One key challenge to address when developing virtual assembly training is the extensive authoring effort for setting up virtual environments. Although knowledge from the product and manufacturing design is available and could be used for virtual training, a concept for integration of this data is still missing. This paper presents the design of a platform which transfers available enterprise data into a unified model for virtual training and thus enables virtual training of workers at the assembly line before the physical prototypes exist. The data requirements and constraints stemming from industrial partners involved in the project will be discussed. A second hurdle for virtual training is the insufficient user integration and acceptance. In this context, the paper introduces an innovative hardware set-up for game-based user interaction, which has been chosen to enhance user involvement and acceptance of virtual training.

Enabling virtual assembly training in and beyond the automotive industry

To ailnultaneously model 3D objects efficiently and precisely seems somewhat contradictory. Several approaches have been clcvclopcd to do tither inaccurate but fast 3D sketching using 2D or 3D input devices or to model precisely with conventional 2D techniques, We believe that the reason why 3D input devices have not been successful outside of imprecise sketching is due to a lack of appropriate rntcraction techniques that drive 3D devices to their lull potential.

André Stork

Papers

A multi-layered architecture for sketch-based interaction within virtual environments

Online 4d reconstruction using multi-images available under open access

Enabling virtual assembly training in and beyond the automotive industry

Efficient and precise solid modelling using a 3D input device

Enhancing a Commercial 3D CAD System by CSCW Functionality for Enabling Co-Operative Modelling via WAN