Real-time Augmented Reality Applications Research Articles

Strategy for Creating AR Applications in Static and Dynamic Environments Using SLAM- and Marker Detector-Based Tracking

Recently, simultaneous localization and mapping (SLAM) has received considerable attention in augmented reality (AR) libraries and applications. Although the assumption of scene rigidity is common in most visual SLAMs, this assumption limits the possibilities of AR applications in various real-world environments. In this paper, we propose a new tracking system that integrates SLAM with a marker detection module for real-time AR applications in static and dynamic environments. Because the proposed system assumes that the marker is movable, SLAM performs tracking and mapping of the static scene except for the marker, and the marker detector estimates the 3-dimensional pose of the marker attached to the dynamic object. We can place SLAM maps, cameras, and dynamic objects (markers) on the same coordinate system, and we can also accurately augment AR resources in real-time on both the static scene and dynamic objects simultaneously. Additionally, having a static map of the scene in advance has the advantage of being able to perform tracking of static and dynamic environments with mapping disabled. In this paper, we evaluate whether the proposed tracking system is suitable for AR applications and describe a strategy for creating AR applications in static and dynamic environments with a demonstration.

Adaptive Monocular Visual-Inertial SLAM for Real-Time Augmented Reality Applications in Mobile Devices.

Simultaneous localization and mapping (SLAM) is emerging as a prominent issue in computer vision and next-generation core technology for robots, autonomous navigation and augmented reality. In augmented reality applications, fast camera pose estimation and true scale are important. In this paper, we present an adaptive monocular visual–inertial SLAM method for real-time augmented reality applications in mobile devices. First, the SLAM system is implemented based on the visual–inertial odometry method that combines data from a mobile device camera and inertial measurement unit sensor. Second, we present an optical-flow-based fast visual odometry method for real-time camera pose estimation. Finally, an adaptive monocular visual–inertial SLAM is implemented by presenting an adaptive execution module that dynamically selects visual–inertial odometry or optical-flow-based fast visual odometry. Experimental results show that the average translation root-mean-square error of keyframe trajectory is approximately 0.0617 m with the EuRoC dataset. The average tracking time is reduced by 7.8%, 12.9%, and 18.8% when different level-set adaptive policies are applied. Moreover, we conducted experiments with real mobile device sensors, and the results demonstrate the effectiveness of performance improvement using the proposed method.

Live intrinsic video

Intrinsic video decomposition refers to the fundamentally ambiguous task of separating a video stream into its constituent layers, in particular reflectance and shading layers. Such a decomposition is the basis for a variety of video manipulation applications, such as realistic recoloring or retexturing of objects. We present a novel variational approach to tackle this underconstrained inverse problem at real-time frame rates, which enables on-line processing of live video footage. The problem of finding the intrinsic decomposition is formulated as a mixed variational ℓ 2 - ℓ p -optimization problem based on an objective function that is specifically tailored for fast optimization. To this end, we propose a novel combination of sophisticated local spatial and global spatio-temporal priors resulting in temporally coherent decompositions at real-time frame rates without the need for explicit correspondence search. We tackle the resulting high-dimensional, non-convex optimization problem via a novel data-parallel iteratively reweighted least squares solver that runs on commodity graphics hardware. Real-time performance is obtained by combining a local-global solution strategy with hierarchical coarse-to-fine optimization. Compelling real-time augmented reality applications, such as recoloring, material editing and retexturing, are demonstrated in a live setup. Our qualitative and quantitative evaluation shows that we obtain high-quality real-time decompositions even for challenging sequences. Our method is able to outperform state-of-the-art approaches in terms of runtime and result quality -- even without user guidance such as scribbles.

Moving object detection for real-time augmented reality applications in a GPGPU

The last generation of consumer electronic devices is endowed with Augmented Reality (AR) tools. These tools require moving object detection strategies, which should be fast and efficient, to carry out higher level object analysis tasks. We propose a lightweight spatio-temporal-based non-parametric background-foreground modeling strategy in a General Purpose Graphics Processing Unit (GPGPU), which provides real-time high-quality results in a great variety of scenarios and is suitable for AR applications.

광류를 사용한 빠른 자연특징 추적

시각기반 증강현실을 구현하기 위한 추적 방법들은 정형 패턴 마커를 가정하는 마커 추적기법과 영상 특징점을 추출하여 이를 추적하는 자연특징 추적기법으로 분류된다. 마커 추적기법은 빠른 마커의 추출 및 인식이 가능하여 모바일 기기에서도 실시간 처리가 가능하다. 한편 자연 특징 추적기법의 경우는 입력 영상의 다양성을 고려해야 하므로 계산량이 많은 처리과정을 거쳐야 한다. 따라서 저사양의 모바일 기기에서는 빠른 실시간 처리에 어려움이 있다. 기존의 자연특징 추적에서는 입력되는 카메라 영상의 매 프레임마다 특징점을 추출하고 패턴매칭 과정을 거친다. 다수의 자연특징점들을 추출하는 과정과 패턴매칭 과정은 계산량이 많아 실시간 응용에 많은 제약을 가하는 요인으로 작용한다. 특히 등록된 패턴의 개수가 증가될수록 패턴매칭 과정의 처리시간도 증가하게 된다. 본 논문에서는 이러한 단점을 해결하고자 자연특징 추적 과정에 광류를 사용하여 모바일 기기에서의 실시간 동작이 가능하도록 하였다. 패턴매칭에 사용된 특징점들은 다음의 연속 프레임에서 광류추적 기법을 적용하여 대응점들을 빠르게 찾도록 하였다. 또한 추적 과정에서 소실되는 특징점의 수에 비례하여 새로운 특징점들을 추가하여 특징점의 전체 개수는 일정 수준으로 유지되도록 하였다. 실험 결과 제안하는 추적 방법은 자연특징점 추적 시간을 상당히 단축시킬 뿐만 아니라 카메라 자세 추정 결과도 더욱 안정시킴을 보여주었다. Visual tracking techniques for Augmented Reality are classified as either a marker tracking approach or a natural feature tracking approach. Marker-based tracking algorithms can be efficiently implemented sufficient to work in real-time on mobile devices. On the other hand, natural feature tracking methods require a lot of computationally expensive procedures. Most previous natural feature tracking methods include heavy feature extraction and pattern matching procedures for each of the input image frame. It is difficult to implement real-time augmented reality applications including the capability of natural feature tracking on low performance devices. The required computational time cost is also in proportion to the number of patterns to be matched. To speed up the natural feature tracking process, we propose a novel fast tracking method based on optical flow. We implemented the proposed method on mobile devices to run in real-time and be appropriately used with mobile augmented reality applications. Moreover, during tracking, we keep up the total number of feature points by inserting new feature points proportional to the number of vanished feature points. Experimental results showed that the proposed method reduces the computational cost and also stabilizes the camera pose estimation results.

Vision-based real-time camera match moving using a known marker

We propose a fast and stable camera match-moving method aimed for real-time augmented reality applications. A known marker is used for fast and robust detection of marker points and for stable camera pose estimation. From the detected image points of a known marker on a single frame, we estimate the camera position and translation parameters. The entire pose estimation process is linear and initial estimates are not required. The most suitable reference point for the pose estimation is automatically chosen by investigating the depth variation. A planar marker is also allowed, since our linear method handles rank deficient cases. As an application of the proposed method, we implement a video augmentation system that replaces the marker in image frames with a virtual graphical object during the marker tracking. Experimental results show that the proposed camera tracking method is robust and fast enough for interactive video-based applications.

Virtual Visual Servoing: a framework for real-time augmented reality

This paper presents a framework to achieve real-time augmented reality applications. We propose a framework based on the visual servoing approach well known in robotics. We consider pose or viewpoint computation as a similar problem to visual servoing. It allows one to take advantage of all the research that has been carried out in this domain in the past. The proposed method features simplicity, accuracy, efficiency, and scalability wrt. to the camera model as well as wrt. the features extracted from the image. We illustrate the efficiency of our approach on augmented reality applications with various real image sequences.