Cultural Heritage in Marker-Less Augmented Reality: A Survey
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paper_title: Real-time markerless tracking for augmented reality: the virtual visual servoing framework

paper_content:

Tracking is a very important research subject in a real-time augmented reality context. The main requirements for trackers are high accuracy and little latency at a reasonable cost. In order to address these issues, a real-time, robust, and efficient 3D model-based tracking algorithm is proposed for a "video see through" monocular vision system. The tracking of objects in the scene amounts to calculating the pose between the camera and the objects. Virtual objects can then be projected into the scene using the pose. In this paper, nonlinear pose estimation is formulated by means of a virtual visual servoing approach. In this context, the derivation of point-to-curves interaction matrices are given for different 3D geometrical primitives including straight lines, circles, cylinders, and spheres. A local moving edges tracker is used in order to provide real-time tracking of points normal to the object contours. Robustness is obtained by integrating an M-estimator into the visual control law via an iteratively reweighted least squares implementation. This approach is then extended to address the 3D model-free augmented reality problem. The method presented in this paper has been validated on several complex image sequences including outdoor environments. Results show the method to be robust to occlusion, changes in illumination, and mistracking.
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paper_title: A markerless registration method for augmented reality based on affine properties

paper_content:

This paper presents a markerless registration approach for Augmented Reality (AR) systems based on the Kanade-Lucas-Tomasi (KLT) natural feature tracker and the affine reconstruction and reprojection techniques. First, the KLT tracker is used to track the corresponding feature points in two control images. Next, four planar points are specified in each control image to set up the world coordinate system. The affine reconstruction and reprojection techniques are used to estimate the image projections of these four specified planar points in the live video sequence, and these image projections are used to estimate the camera pose in real time. A primitive approach that illustrates the basic idea is first discussed and a robust method is given to improve the resistance to the noise. Pre-defined markers are not required in the proposed approach. The virtual models can still be registered on the proper positions using the proposed method even if the specified region is occluded during the registration process.
---
paper_title: Survey of Shadow Volume Algorithms in Computer Graphics

paper_content:

AbstractThis study will provide an overview of popular and famous algorithms and techniques in shadow generation based on shadow volumes. It characterizes well-known techniques, describing each of them in detail, and discusses the advantages and drawbacks of each. Basic ideas, improvements, and future works of the techniques are also comprehensively summarized and analyzed in depth. Often, programmers have difficulty selecting an appropriate shadow generation algorithm based on shadow volumes that is specific to their purpose. We have classified and systemized these techniques. The main goal of this paper is to provide researchers with background on a progress of shadow volume techniques so as to make it easier for researchers to choose the method best suited to their aims. It is also hoped that our analysis will help researchers find solutions to the shortcomings of each technique.
---
paper_title: A Stable and Accurate Marker-Less Augmented Reality Registration Method

paper_content:

Markerless Augmented Reality (AR) registration using the standard Homography matrix is unstable, and for image-based registration it has very low accuracy. In this paper, we present a new method to improve the stability and the accuracy of marker-less registration in AR. Based on the Visual Simultaneous Localization and Mapping (V-SLAM) framework, our method adds a three-dimensional dense cloud processing step to the state-of-the-art ORB-SLAM in order to deal with mainly the point cloud fusion and the object recognition. Our algorithm for the object recognition process acts as a stabilizer to improve the registration accuracy during the model to the scene transformation process. This has been achieved by integrating the Hough voting algorithm with the Iterative Closest Points(ICP) method. Our proposed AR framework also further increases the registration accuracy with the use of integrated camera poses on the registration of virtual objects. Our experiments show that the proposed method not only accelerates the speed of camera tracking with a standard SLAM system, but also effectively identifies objects and improves the stability of markerless augmented reality applications.
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paper_title: Traversable interfaces between real and virtual worlds

paper_content:

Traversable interfaces establish the illusion that virtual and physical worlds are joined together and that users can physically cross from one to the other. Our design for a traversable interface combines work on tele-embodiment, mixed reality boundaries and virtual environments. It also exploits non-solid projection surfaces, of which we describe four examples. Our design accommodates the perspectives of users who traverse the interface and also observers who are present in the connected physical and virtual worlds, an important consideration for performance and entertainment applications. A demonstrator supports encounters between members of our laboratory and remote visitors.
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paper_title: ReVitAge: Realistic virtual heritage taking shadows and sky illumination into account

paper_content:

Abstract Today's modern organizations are striving hard to trace the beginnings of human civilization and maintain cultural heritage throughout the world; as a result the need for an integrative technique materializing this dream is felt more than ever. Realistic historical buildings in outdoor rendering Augmented Reality (AR) systems require sophisticated effects such as shadows, lighting and the ability to reveal the effect of sky dome illumination on virtual as well as real objects. In this project, the sun position and sky colour are simulated using Julian dating and Perez model respectively. The historical buildings are pre-created using LightWave 3D. An AR system is created using a new marker-less camera setting. The sky illumination is exerted on the virtual historical buildings using a Hemicube Radiosity technique. We have tested the proposed method on Portuguese Malacca heritage building (Melaka, Malaysia) in different places to reveal the auto-adjustment of the system in the case of shadow positioning, lighting and the sky's illumination. The final system could be installed on HMD (head mounted display) or in our device called ReVitAge to show the realistic reconstructed virtual heritage buildings, taking the main outdoor illumination components into account. Throughout this method, listed heritage buildings can be revived in the minds of people from different backgrounds who share the same ambitious dream. It is strongly hoped that this idea can make historical buildings a virtual reality; closer to people's hearts.
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paper_title: A marker-based augmented reality system for mobile devices

paper_content:

Given the rate at which mobile devices are adopted by the general public, we are at a point where many of us own a smart phone. Currently, this makes them the most affordable interfaces for augmented reality. However, with respect to augmented reality, smartphones present some limitations: location tracking is, on a large scale, supported only for outdoor environments and the content types that can be displayed to the user are generally limited. We therefore propose a marker-based tracking system which detects QR-codes on the camera capture and overlays rich media obtained from a server. We further analyze the performance implications of such a system, by breaking down the processing into pipelined stages and providing a mechanism of skipping frames from the capture in order to give a fast on-screen response.
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paper_title: Camera pose estimation under dynamic intrinsic parameter change for augmented reality

paper_content:

In this paper, we propose a method for estimating the camera pose for an environment in which the intrinsic camera parameters change dynamically. In video see-through augmented reality (AR) technology, image-based methods for estimating the camera pose are used to superimpose virtual objects onto the real environment. In general, video see-through-based AR cannot change the image magnification that results from a change in the camera's field-of-view because of the difficulty of dealing with changes in the intrinsic camera parameters. To remove this limitation, we propose a novel method for simultaneously estimating the intrinsic and extrinsic camera parameters based on an energy minimization framework. Our method is composed of both online and offline stages. An intrinsic camera parameter change depending on the zoom values is calibrated in the offline stage. Intrinsic and extrinsic camera parameters are then estimated based on the energy minimization framework in the online stage. In our method, two energy terms are added to the conventional marker-based method to estimate the camera parameters: reprojection errors based on the epipolar constraint and the constraint of the continuity of zoom values. By using a novel energy function, our method can accurately estimate intrinsic and extrinsic camera parameters. We confirmed experimentally that the proposed method can achieve accurate camera parameter estimation during camera zooming. Graphical abstractDisplay Omitted HighlightsWe propose an intrinsic and extrinsic camera parameter estimation method.We extended a conventional marker-based method by adding two energy terms.Camera parameters are estimated accurately using new energy function.The effectiveness of our method is shown in simulated and real environments.
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paper_title: Markerless Pose Tracking for Augmented Reality

paper_content:

In this paper a new approach is presented for markerless pose tracking in augmented reality. Using a tracking by detection approach, we estimate the 3D camera pose by detecting natural feature points in each input frame and building correspondences between 2D feature points. Instead of modeling the 3D environment, which is changing constantly and dynamically, we use a virtual square to define a 3D reference coordinate system. Camera pose can hence be estimated relative to it and the calculated 3D pose parameters can be used to render virtual objects into the real world. We propose and implement several strategies for robust matching, pose estimation and refinement. Experimental evaluation has shown that the approach is capable of online pose tracking and augmentation.
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paper_title: Camera pose estimation for augmented reality in a small indoor dynamic scene

paper_content:

Camera pose estimation remains a challenging task for augmented reality (AR) applications. Simultaneous localization and mapping (SLAM)-based methods are able to estimate the six degrees of freedom camera motion while constructing a map of an unknown environment. However, these methods do not provide any reference for where to insert virtual objects since they do not have any information about scene structure and may fail in cases of occlusion of three-dimensional (3-D) map points or dynamic objects. This paper presents a real-time monocular piece wise planar SLAM method using the planar scene assumption. Using planar structures in the mapping process allows rendering virtual objects in a meaningful way on the one hand and improving the precision of the camera pose and the quality of 3-D reconstruction of the environment by adding constraints on 3-D points and poses in the optimization process on the other hand. We proposed to benefit from the 3-D planes rigidity motion in the tracking process to enhance the system robustness in the case of dynamic scenes. Experimental results show that using a constrained planar scene improves our system accuracy and robustness compared with the classical SLAM systems.
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paper_title: Augmented reality in a wide area sentient environment

paper_content:

Augmented reality (AR) both exposes and supplements the user's view of the real world. Previous AR work has focussed on the close registration of real and virtual objects, which requires very accurate real-time estimates of head position and orientation. Most of these systems have been tethered and restricted to small volumes. In contrast, we have chosen to concentrate on allowing the AR user to roam freely within an entire building. At AT&T Laboratories Cambridge we provide personnel with AR services using data from an ultrasonic tracking system, called the Bat system, which has been deployed building-wide. We have approached the challenge of implementing a wide-area, in-building AR system in two different ways. The first uses a head-mounted display connected to a laptop, which combines sparse position measurements from the Bat system with more frequent rotational information from an inertial tracker to render annotations and virtual objects that relate to or coexist with the real world. The second uses a PDA to provide a convenient portal with which the user can quickly view the augmented world. These systems can be used to annotate the world in a more-or-less seamless way, allowing a richer interaction with both real and virtual objects.
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paper_title: Markerless Augmented Reality for Robotic Helicoptor Applications

paper_content:

The objective of this research is to apply markerless Augmented Reality (AR) techniques to aid in the visualisation of robotic helicopter related tasks. Conventional robotic AR applications work well with markers in prepared environments but are infeasible in outdoor settings. In this paper, we present preliminary results from a real time markerless AR system for tracking natural features in an agricultural scene. By constructing a virtual marker under a known initial configuration of the robotic helicopter, camera and the ground plane, the camera pose can be continuously tracked using the natural features from the image sequence to perform augmentation of virtual objects. The experiments are simulated on a mock-up model of an agricultural farm and the results show that the current AR system is capable of tracking the camera pose accurately for translational motions and roll rotations. Future work includes reducing jitter in the virtual marker vertices to improve camera pose estimation accuracy for pitch and yaw rotations, and implementing feature recovery algorithms.
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paper_title: Bateau ivre: an artistic markerless outdoor mobile augmented reality installation on a riverboat

paper_content:

Bateau Ivre is a project presented on the Seine River to make a large audience aware of the possible developments of Augmented Reality through an artistic installation in a mobile outdoor environment. The installation could be viewed from a ship by a large audience without specific equipment, through nightly video-projection on the River banks. The augmentation of the physical world was implemented through real-time image processing for live special effects such as contouring, particles, or non-realistic rendering. The artistic purpose of the project was to immerge the audience into a non-realistic view of the River banks that would differ from the traditional tourist tours that highlight the main landmarks of Paris classical architecture. The implemented software applied standard algorithms for special effects to a live video stream and reprojected these effects on the captured scenes to combine the physical world with its modified image. An analysis of the project output reveals that the impact of the effects in mobile SAR varies a lot, and does not correspond to the visual impact on a standard desktop screen.
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paper_title: Improvement of registration accuracy of a handheld augmented reality system for urban landscape simulation

paper_content:

Abstract The need for visual landscape assessment in large-scale projects for the evaluation of the effects of a particular project on the surrounding landscape has grown in recent years. Augmented reality (AR) has been considered for use as a landscape simulation system in which a landscape assessment object created by 3D models is included in the present surroundings. With the use of this system, the time and the cost needed to perform a 3DCG modeling of present surroundings, which is a major issue in virtual reality, are drastically reduced. This research presents the development of a 3D map-oriented handheld AR system that achieves geometric consistency using a 3D map to obtain position data instead of GPS, which has low position information accuracy, particularly in urban areas. The new system also features a gyroscope sensor to obtain posture data and a video camera to capture live video of the present surroundings. All these components are mounted in a smartphone and can be used for urban landscape assessment. Registration accuracy is evaluated to simulate an urban landscape from a short- to a long-range scale. The latter involves a distance of approximately 2000 m. The developed AR system enables users to simulate a landscape from multiple and long-distance viewpoints simultaneously and to walk around the viewpoint fields using only a smartphone. This result is the tolerance level of landscape assessment. In conclusion, the proposed method is evaluated as feasible and effective.
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paper_title: Exploring MARS: Developing Indoor and Outdoor User Interfaces to a Mobile Augmented Reality System

paper_content:

We describe an experimental mobile augmented reality system (MARS) testbed that employs different user interfaces to allow outdoor and indoor users to access and manage information that is spatially registered with the real world. Outdoor users can experience spatialized multimedia presentations that are presented on a head-tracked, see-through, head-worn display used in conjunction with a hand-held pen-based computer. Indoor users can get an overview of the outdoor scene and communicate with outdoor users through a desktop user interface or a head- and hand-tracked immersive augmented reality user interface.
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paper_title: ReVitAge: Realistic virtual heritage taking shadows and sky illumination into account

paper_content:

Abstract Today's modern organizations are striving hard to trace the beginnings of human civilization and maintain cultural heritage throughout the world; as a result the need for an integrative technique materializing this dream is felt more than ever. Realistic historical buildings in outdoor rendering Augmented Reality (AR) systems require sophisticated effects such as shadows, lighting and the ability to reveal the effect of sky dome illumination on virtual as well as real objects. In this project, the sun position and sky colour are simulated using Julian dating and Perez model respectively. The historical buildings are pre-created using LightWave 3D. An AR system is created using a new marker-less camera setting. The sky illumination is exerted on the virtual historical buildings using a Hemicube Radiosity technique. We have tested the proposed method on Portuguese Malacca heritage building (Melaka, Malaysia) in different places to reveal the auto-adjustment of the system in the case of shadow positioning, lighting and the sky's illumination. The final system could be installed on HMD (head mounted display) or in our device called ReVitAge to show the realistic reconstructed virtual heritage buildings, taking the main outdoor illumination components into account. Throughout this method, listed heritage buildings can be revived in the minds of people from different backgrounds who share the same ambitious dream. It is strongly hoped that this idea can make historical buildings a virtual reality; closer to people's hearts.
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paper_title: Markerless Augmented Reality Utilizing Gyroscope to Demonstrate the Position of Dewata Nawa Sanga

paper_content:

Dewata Nawa Sanga in Hinduism has an important role as the foundation of the religious concept implemented by Hindus in Bali, Indonesia. It has the meaning of nine deities or manifestations of Ida Sang Hyang Widhi Wasa (God Almighty) that guard or control the nine wind direction. Dewata Nawa Sanga in terms of education in Bali has been learned by the elementary school students. However, in social life the concept of Dewata Nawa Sanga itself has not been attached and understood by all Balinese Hinduism yet. Based on the problem in social life, there is an idea to develop Markerless Augmented Reality Utilizing Gyroscope to Demonstrate the Position of Dewata Nawa Sanga . This application is designed to know, recognize, and understand the characteristics of Dewata Nawa Sanga using gyroscope. This sensor serves to fulfill the object of the deities in the coordinates to be determined. Furthermore, it serves to provide information about Dewata Nawa Sanga along with the innovative and informative 3D animation. The result of usefulness questionnaire of this application percentage value average is 88.4%. It can be concluded that AR Dewata Nawa Sanga is very useful and helpful for learners in exploring the Dewata Nawa Sanga position in a real-world environment. The result of usability and satisfaction questionnaire of this application percentage value average is 84.8%. It shows that the application is very useful for the participants to learn Dewata Nawa Sanga and very satisfied to use.
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paper_title: Survey of Shadow Volume Algorithms in Computer Graphics

paper_content:

AbstractThis study will provide an overview of popular and famous algorithms and techniques in shadow generation based on shadow volumes. It characterizes well-known techniques, describing each of them in detail, and discusses the advantages and drawbacks of each. Basic ideas, improvements, and future works of the techniques are also comprehensively summarized and analyzed in depth. Often, programmers have difficulty selecting an appropriate shadow generation algorithm based on shadow volumes that is specific to their purpose. We have classified and systemized these techniques. The main goal of this paper is to provide researchers with background on a progress of shadow volume techniques so as to make it easier for researchers to choose the method best suited to their aims. It is also hoped that our analysis will help researchers find solutions to the shortcomings of each technique.
---
paper_title: Generation of virtual models of cultural heritage

paper_content:

Abstract Different techniques and tools currently exist to generate three-dimensional models of small elements, buildings and cities. Apart from being easier to interpret than two-dimensional drawings, these models facilitate data necessary for reconstruction projects, preservation or rehabilitation of the architectural or archaeological heritage. Traditional surveying only enables us to obtain discrete information of the characteristic lines that define each surface, edge, slope change etc. whereas work with massive capture techniques allows us to obtain continuous points of the surfaces. Photogrammetry or laser scanning combined with conventional photography provides information of the building in addition to its geometry. We carried out a review of the different techniques showing the advantages and disadvantages of each technique as well as the information that can be obtained by applying these techniques to the survey of the great Gate of Antioch in the town of Aleppo, declared a World Heritage Site by UNESCO in 1986, in Syria.
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paper_title: Cultural Heritage Layers: Integrating Historic Media in Augmented Reality

paper_content:

In this paper we are presenting Cultural Heritage Layers, an approach that enables the visualization of historic media like drawings, paintings and photographs of buildings and historic scenes seamlessly superimposed on reality via video see through using X3D. This enables simple, inexpensive and sustainable Augmented Reality applications in the cultural heritage and architectural area based on industry standards. The main idea is to use existing historic media from archives and superimpose them seamlessly on reality at the right spot. These locative layers are context sensitively telling the location's history and create the impression of a virtual time journey. The registration of the virtual objects in the video images is provided by a robust 6DOF tracking framework based on two technologies that work in tandem: an initialization step based on Randomized Trees and a frame-to-frame tracking phase based on KLT. The entire application runs in real time on current Ultra Mobile PCs and MIDs.
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paper_title: ReVitAge: Realistic virtual heritage taking shadows and sky illumination into account

paper_content:

Abstract Today's modern organizations are striving hard to trace the beginnings of human civilization and maintain cultural heritage throughout the world; as a result the need for an integrative technique materializing this dream is felt more than ever. Realistic historical buildings in outdoor rendering Augmented Reality (AR) systems require sophisticated effects such as shadows, lighting and the ability to reveal the effect of sky dome illumination on virtual as well as real objects. In this project, the sun position and sky colour are simulated using Julian dating and Perez model respectively. The historical buildings are pre-created using LightWave 3D. An AR system is created using a new marker-less camera setting. The sky illumination is exerted on the virtual historical buildings using a Hemicube Radiosity technique. We have tested the proposed method on Portuguese Malacca heritage building (Melaka, Malaysia) in different places to reveal the auto-adjustment of the system in the case of shadow positioning, lighting and the sky's illumination. The final system could be installed on HMD (head mounted display) or in our device called ReVitAge to show the realistic reconstructed virtual heritage buildings, taking the main outdoor illumination components into account. Throughout this method, listed heritage buildings can be revived in the minds of people from different backgrounds who share the same ambitious dream. It is strongly hoped that this idea can make historical buildings a virtual reality; closer to people's hearts.
---
paper_title: A markerless registration method for augmented reality based on affine properties

paper_content:

This paper presents a markerless registration approach for Augmented Reality (AR) systems based on the Kanade-Lucas-Tomasi (KLT) natural feature tracker and the affine reconstruction and reprojection techniques. First, the KLT tracker is used to track the corresponding feature points in two control images. Next, four planar points are specified in each control image to set up the world coordinate system. The affine reconstruction and reprojection techniques are used to estimate the image projections of these four specified planar points in the live video sequence, and these image projections are used to estimate the camera pose in real time. A primitive approach that illustrates the basic idea is first discussed and a robust method is given to improve the resistance to the noise. Pre-defined markers are not required in the proposed approach. The virtual models can still be registered on the proper positions using the proposed method even if the specified region is occluded during the registration process.
---
paper_title: ReVitAge: Realistic virtual heritage taking shadows and sky illumination into account

paper_content:

Abstract Today's modern organizations are striving hard to trace the beginnings of human civilization and maintain cultural heritage throughout the world; as a result the need for an integrative technique materializing this dream is felt more than ever. Realistic historical buildings in outdoor rendering Augmented Reality (AR) systems require sophisticated effects such as shadows, lighting and the ability to reveal the effect of sky dome illumination on virtual as well as real objects. In this project, the sun position and sky colour are simulated using Julian dating and Perez model respectively. The historical buildings are pre-created using LightWave 3D. An AR system is created using a new marker-less camera setting. The sky illumination is exerted on the virtual historical buildings using a Hemicube Radiosity technique. We have tested the proposed method on Portuguese Malacca heritage building (Melaka, Malaysia) in different places to reveal the auto-adjustment of the system in the case of shadow positioning, lighting and the sky's illumination. The final system could be installed on HMD (head mounted display) or in our device called ReVitAge to show the realistic reconstructed virtual heritage buildings, taking the main outdoor illumination components into account. Throughout this method, listed heritage buildings can be revived in the minds of people from different backgrounds who share the same ambitious dream. It is strongly hoped that this idea can make historical buildings a virtual reality; closer to people's hearts.
---
paper_title: A Stable and Accurate Marker-Less Augmented Reality Registration Method

paper_content:

Markerless Augmented Reality (AR) registration using the standard Homography matrix is unstable, and for image-based registration it has very low accuracy. In this paper, we present a new method to improve the stability and the accuracy of marker-less registration in AR. Based on the Visual Simultaneous Localization and Mapping (V-SLAM) framework, our method adds a three-dimensional dense cloud processing step to the state-of-the-art ORB-SLAM in order to deal with mainly the point cloud fusion and the object recognition. Our algorithm for the object recognition process acts as a stabilizer to improve the registration accuracy during the model to the scene transformation process. This has been achieved by integrating the Hough voting algorithm with the Iterative Closest Points(ICP) method. Our proposed AR framework also further increases the registration accuracy with the use of integrated camera poses on the registration of virtual objects. Our experiments show that the proposed method not only accelerates the speed of camera tracking with a standard SLAM system, but also effectively identifies objects and improves the stability of markerless augmented reality applications.
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paper_title: From 3D reconstruction to virtual reality: A complete methodology for digital archaeological exhibition

paper_content:

Abstract For nearly two decades, virtual reality (VR) technologies have been employed in the field of cultural heritage for various purposes. The safeguard, the protection and the fruition of the remains of the past have gained a powerful tool, thanks to the potentialities of immersive visualization and 3D reconstruction of archaeological sites and finds. VR applications based on videogame technologies are known for their realism and fluid interactivity, but the choice of the fittest technologies remains a complex task because there is an ample number of hardware devices and software development kits. Moreover the design of a VR application for cultural heritage requires several different professional skills and presents a certain complexity in coordination and management. This paper presents strategies to overcome these problems, by suggesting some guidelines for the development of VR systems for cultural heritage. It illustrates a complete methodology to create a virtual exhibition system, based on realistic high-quality 3D models of archaeological finds (reconstructed using a 3D Scanner and a high definition camera) and a low-cost multimedia stereoscopic system called MNEME, which allows the user to interact in a free and easy way with a rich collection of archaeological finds. The solution we propose is intended to be easy to transport and fully usable by different user typologies, without any external assistance or supervision.
---
paper_title: ReVitAge: Realistic virtual heritage taking shadows and sky illumination into account

paper_content:

Abstract Today's modern organizations are striving hard to trace the beginnings of human civilization and maintain cultural heritage throughout the world; as a result the need for an integrative technique materializing this dream is felt more than ever. Realistic historical buildings in outdoor rendering Augmented Reality (AR) systems require sophisticated effects such as shadows, lighting and the ability to reveal the effect of sky dome illumination on virtual as well as real objects. In this project, the sun position and sky colour are simulated using Julian dating and Perez model respectively. The historical buildings are pre-created using LightWave 3D. An AR system is created using a new marker-less camera setting. The sky illumination is exerted on the virtual historical buildings using a Hemicube Radiosity technique. We have tested the proposed method on Portuguese Malacca heritage building (Melaka, Malaysia) in different places to reveal the auto-adjustment of the system in the case of shadow positioning, lighting and the sky's illumination. The final system could be installed on HMD (head mounted display) or in our device called ReVitAge to show the realistic reconstructed virtual heritage buildings, taking the main outdoor illumination components into account. Throughout this method, listed heritage buildings can be revived in the minds of people from different backgrounds who share the same ambitious dream. It is strongly hoped that this idea can make historical buildings a virtual reality; closer to people's hearts.
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paper_title: Augmented reality and GIS: On the possibilities and limits of markerless AR

paper_content:

The application of Augmented Reality (AR) in the geo-spatial domain offers huge potentials: AR can visualize invisible properties of spatial entities, can display historic data for them, or can help in finding places. Whatever the application is, AR in the geo-spatial domain will often be purely sensor based, thus without the help of visual or sensory markers. In this paper we analyse the achievable accuracy of AR projections under everyday conditions with consumer hardware. We can show that AR can be applied in applications in smaller geographic scale, but is not sufficient if it comes to the preciseness required when inspecting infrastructural data of small scale.
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paper_title: Real-time markerless tracking for augmented reality: the virtual visual servoing framework

paper_content:

Tracking is a very important research subject in a real-time augmented reality context. The main requirements for trackers are high accuracy and little latency at a reasonable cost. In order to address these issues, a real-time, robust, and efficient 3D model-based tracking algorithm is proposed for a "video see through" monocular vision system. The tracking of objects in the scene amounts to calculating the pose between the camera and the objects. Virtual objects can then be projected into the scene using the pose. In this paper, nonlinear pose estimation is formulated by means of a virtual visual servoing approach. In this context, the derivation of point-to-curves interaction matrices are given for different 3D geometrical primitives including straight lines, circles, cylinders, and spheres. A local moving edges tracker is used in order to provide real-time tracking of points normal to the object contours. Robustness is obtained by integrating an M-estimator into the visual control law via an iteratively reweighted least squares implementation. This approach is then extended to address the 3D model-free augmented reality problem. The method presented in this paper has been validated on several complex image sequences including outdoor environments. Results show the method to be robust to occlusion, changes in illumination, and mistracking.
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paper_title: Going out: robust model-based tracking for outdoor augmented reality

paper_content:

This paper presents a model-based hybrid tracking system for outdoor augmented reality in urban environments enabling accurate, realtime overlays for a handheld device. The system combines several well-known approaches to provide a robust experience that surpasses each of the individual components alone: an edge-based tracker for accurate localisation, gyroscope measurements to deal with fast motions, measurements of gravity and magnetic field to avoid drift, and a back store of reference frames with online frame selection to re-initialize automatically after dynamic occlusions or failures. A novel edge-based tracker dispenses with the conventional edge model, and uses instead a coarse, but textured, 3D model. This yields several advantages: scale-based detail culling is automatic, appearance-based edge signatures can be used to improve matching and the models needed are more commonly available. The accuracy and robustness of the resulting system is demonstrated with comparisons to map-based ground truth data.
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paper_title: Multithreaded Hybrid Feature Tracking for Markerless Augmented Reality

paper_content:

We describe a novel markerless camera tracking approach and user interaction methodology for augmented reality (AR) on unprepared tabletop environments. We propose a real-time system architecture that combines two types of feature tracking. Distinctive image features of the scene are detected and tracked frame-to-frame by computing optical flow. In order to achieve real-time performance, multiple operations are processed in a synchronized multi-threaded manner: capturing a video frame, tracking features using optical flow, detecting distinctive invariant features, and rendering an output frame. We also introduce user interaction methodology for establishing a global coordinate system and for placing virtual objects in the AR environment by tracking a user's outstretched hand and estimating a camera pose relative to it. We evaluate the speed and accuracy of our hybrid feature tracking approach, and demonstrate a proof-of-concept application for enabling AR in unprepared tabletop environments, using bare hands for interaction.
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paper_title: Generation of virtual models of cultural heritage

paper_content:

Abstract Different techniques and tools currently exist to generate three-dimensional models of small elements, buildings and cities. Apart from being easier to interpret than two-dimensional drawings, these models facilitate data necessary for reconstruction projects, preservation or rehabilitation of the architectural or archaeological heritage. Traditional surveying only enables us to obtain discrete information of the characteristic lines that define each surface, edge, slope change etc. whereas work with massive capture techniques allows us to obtain continuous points of the surfaces. Photogrammetry or laser scanning combined with conventional photography provides information of the building in addition to its geometry. We carried out a review of the different techniques showing the advantages and disadvantages of each technique as well as the information that can be obtained by applying these techniques to the survey of the great Gate of Antioch in the town of Aleppo, declared a World Heritage Site by UNESCO in 1986, in Syria.
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paper_title: A Review on Augmented Reality for Virtual Heritage System

paper_content:

Augmented reality is one of the emerging technologies to reconstruct the historical building and monument in the previous era, where the user experiences with the real environment or virtual scene. In education, Virtual Heritage becomes as a platform of learning, motivating and understanding of certain events and historical elements for the students and researchers. The significance of reconstruction of digital culture heritage are to preserve, protect and interpret of our cultural and history. In recent year, there are a number of significant researches and techniques that have been developed, which is focusing on virtual restitution of historical sites. This paper will present an overview on augmented reality in Virtual Heritage system and also consists with the explanation of techniques to reconstruct the historical sites.
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paper_title: Augmented reality for art, design and cultural heritage: system design and evaluation

paper_content:

This paper describes the design of an optical see-through head-mounted display (HMD) system for Augmented Reality (AR). Our goals were to make virtual objects "perfectly" indistinguishable from real objects, wherever the user roams, and to find out to which extent imperfections are hindering applications in art and design. For AR, fast and accurate measuring of head motions is crucial. We made a head-pose tracker for the HMD that uses error-state Kalman filters to fuse data from an inertia tracker with data from a camera that tracks visual markers. This makes on-line head-pose based rendering of dynamic virtual content possible.We measured our system, and found that with an A4-sized marker viewed from > 20° at 5 m distance with an SXGA camera (FOV 108°), the RMS error in the tracker angle was < 0.5° when moving the head slowly. Our Kalman filters suppressed the pose error due to camera delay, which is proportional to the angular and linear velocities, and the dynamic misalignment was comparable to the static misalignment. Applications of artists and designers lead to observations on the profitable use of our AR system. Their exhibitions at world-class museums showed that AR is a powerful tool for disclosing cultural heritage.
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paper_title: A Review on Augmented Reality for Virtual Heritage System

paper_content:

Augmented reality is one of the emerging technologies to reconstruct the historical building and monument in the previous era, where the user experiences with the real environment or virtual scene. In education, Virtual Heritage becomes as a platform of learning, motivating and understanding of certain events and historical elements for the students and researchers. The significance of reconstruction of digital culture heritage are to preserve, protect and interpret of our cultural and history. In recent year, there are a number of significant researches and techniques that have been developed, which is focusing on virtual restitution of historical sites. This paper will present an overview on augmented reality in Virtual Heritage system and also consists with the explanation of techniques to reconstruct the historical sites.
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paper_title: A Review on Augmented Reality for Virtual Heritage System

paper_content:

Augmented reality is one of the emerging technologies to reconstruct the historical building and monument in the previous era, where the user experiences with the real environment or virtual scene. In education, Virtual Heritage becomes as a platform of learning, motivating and understanding of certain events and historical elements for the students and researchers. The significance of reconstruction of digital culture heritage are to preserve, protect and interpret of our cultural and history. In recent year, there are a number of significant researches and techniques that have been developed, which is focusing on virtual restitution of historical sites. This paper will present an overview on augmented reality in Virtual Heritage system and also consists with the explanation of techniques to reconstruct the historical sites.
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paper_title: Usability Engineering for Augmented Reality: Employing User-Based Studies to Inform Design

paper_content:

A major challenge, and thus opportunity, in the field of human-computer interaction and specifically usability engineering is designing effective user interfaces for emerging technologies that have no established design guidelines or interaction metaphors or introduce completely new ways for users to perceive and interact with technology and the world around them. Clearly, augmented reality is one such emerging technology. We propose a usability engineering approach that employs user-based studies to inform design, by iteratively inserting a series of user-based studies into a traditional usability engineering lifecycle to better inform initial user interface designs. We present an exemplar user-based study conducted to gain insight into how users perceive text in outdoor augmented reality settings and to derive implications for design in outdoor augmented reality. We also describe lessons learned from our experiences conducting user-based studies as part of the design process.
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paper_title: Mediating team work for digital heritage archiving

paper_content:

Building digital heritage requires substantial resources in materials, expertise, tools, and cost. Projects supported by governments and academics can only cover a small part of the world's heritage in both time and space dimensions. The preservation coverage problem is most serious in domains where sources of intellectual and cultural heritage may diminish or disappear over time. A central notion that helps resolve these issues is to facilitate global reach of digital technology to sources of valuable heritage. We propose an approach to exploit non-institutional resources for wider participation and coverage in digital heritage endeavor. The approach attempts to replicate institutional digital heritage work by teaming up non-institutional resources and providing standard practice.
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paper_title: The Challenge of Making Augmented Reality Work Outdoors

paper_content:

Despite its potential, Augmented Reality has not received nearly the amount of attention paid to its sibling, Virtual Environments (or Virtual Reality), despite the fact that both fields share a common ancestor. It is often forgotten that Sutherland’s original HMD system was an optical see-through display. While the creators of that system did not explicitly attempt to register virtual 3-D objects with real-world objects, they did have an example of combining virtual and real. The motivation was to allow the user to issue commands. The problem was that the graphics engine did not have sufficient power to draw the menus and commands virtually at interactive rates. Therefore, they physically put large signs with the command names on a real wall, and allowed the user to virtually select one of the real signs by pointing at one with the hand controller. Despite this common root, most efforts following Sutherland’s focused on Virtual Environments. It wasn’t until the late 1980’s and early 1990’s that research in Augmented Reality began again in earnest.
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paper_title: Multithreaded Hybrid Feature Tracking for Markerless Augmented Reality

paper_content:

We describe a novel markerless camera tracking approach and user interaction methodology for augmented reality (AR) on unprepared tabletop environments. We propose a real-time system architecture that combines two types of feature tracking. Distinctive image features of the scene are detected and tracked frame-to-frame by computing optical flow. In order to achieve real-time performance, multiple operations are processed in a synchronized multi-threaded manner: capturing a video frame, tracking features using optical flow, detecting distinctive invariant features, and rendering an output frame. We also introduce user interaction methodology for establishing a global coordinate system and for placing virtual objects in the AR environment by tracking a user's outstretched hand and estimating a camera pose relative to it. We evaluate the speed and accuracy of our hybrid feature tracking approach, and demonstrate a proof-of-concept application for enabling AR in unprepared tabletop environments, using bare hands for interaction.
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paper_title: Cultural Heritage Sites Visualization System based on Outdoor Augmented Reality

paper_content:

Abstract Recently, as importance of history is being emerged, IT-grafted cultural contents industry has been extensively grown. In particular, a study on development of cultural heritage sites, architectural cultural property and digital contents for historical remains restoration by using augmented reality technology has been performed. However, most of the existing restoration system of digital contents is being mainly performed indoors in reality. In this paper, 3D model visualization system of cultural heritage sites by using outdoor augmented reality, not indoor augmented reality, is intended to be presented. Presented visualized system augments 3D model of cultural heritage sites in video image inputted from outdoor by using object panorama, SURF and GPS. And the users may be provided with information for cultural heritage sites without difficulty through this visualized system.
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paper_title: ReVitAge: Realistic virtual heritage taking shadows and sky illumination into account

paper_content:

Abstract Today's modern organizations are striving hard to trace the beginnings of human civilization and maintain cultural heritage throughout the world; as a result the need for an integrative technique materializing this dream is felt more than ever. Realistic historical buildings in outdoor rendering Augmented Reality (AR) systems require sophisticated effects such as shadows, lighting and the ability to reveal the effect of sky dome illumination on virtual as well as real objects. In this project, the sun position and sky colour are simulated using Julian dating and Perez model respectively. The historical buildings are pre-created using LightWave 3D. An AR system is created using a new marker-less camera setting. The sky illumination is exerted on the virtual historical buildings using a Hemicube Radiosity technique. We have tested the proposed method on Portuguese Malacca heritage building (Melaka, Malaysia) in different places to reveal the auto-adjustment of the system in the case of shadow positioning, lighting and the sky's illumination. The final system could be installed on HMD (head mounted display) or in our device called ReVitAge to show the realistic reconstructed virtual heritage buildings, taking the main outdoor illumination components into account. Throughout this method, listed heritage buildings can be revived in the minds of people from different backgrounds who share the same ambitious dream. It is strongly hoped that this idea can make historical buildings a virtual reality; closer to people's hearts.
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Title: Cultural Heritage in Marker-Less Augmented Reality: A Survey

Section 1: Introduction
Description 1: Provide an overview of augmented reality (AR) technology, its applications, and the significance of marker-less AR in cultural heritage.

Section 2: Augmented Reality
Description 2: Define augmented reality, its functionalities, and how it integrates virtual and real environments.

Section 3: Marker-based Augmented Reality
Description 3: Explain the concept and workings of marker-based AR, including its reliance on fiducial markers.

Section 4: Marker-less-based Augmented Reality
Description 4: Describe marker-less AR, its methods, and how it differs from marker-based AR in integrating virtual objects into real environments.

Section 5: Camera Pose Estimation
Description 5: Discuss techniques for camera pose estimation in AR, including relative orientation and planar homography.

Section 6: Outdoor Marker-less-based Augmented Reality
Description 6: Examine the challenges and implementations of marker-less AR in outdoor environments, including various tracking and registration solutions.

Section 7: Cultural Heritage in Augmented Reality
Description 7: Explore the application of AR in cultural heritage, including virtual reconstructions and interactive experiences.

Section 8: Issues with Virtual Heritage in Augmented Reality
Description 8: Identify and explain key issues faced in virtual heritage AR, such as registration, reconstruction, tracking, and location. 

Section 9: 3D Reconstruction Techniques for Cultural Heritage
Description 9: Outline various 3D reconstruction techniques used in AR for cultural heritage, including image-based and range-based modelling.

Section 10: Augmented Reality Location
Description 10: Discuss AR implementations in different site contexts, focusing on both indoor and outdoor heritage sites and the challenges involved.

Section 11: Conclusion
Description 11: Summarize the major findings of the survey and the future directions for marker-less AR in cultural heritage.