In mixed reality using video see-through displays, various optical effects can be simulated for representing a transparent object. However, consumer-available OST-HMDs can not reproduce some of their effects correctly because of its mechanism. There has been little discussion concerning to what extent such transparent objects can be represented realistically. In this demonstration, we will show how effective each for combination of existing methods is.

Virtual shadows provide important cues to determine the positional relationship between virtual objects and a real scene. However, it' s difficult to render shadows in the real scene on optical see-through head-mounted displays without occlusion-capability. In the previous work, we cast virtual shadows not with physical light attenuation but with brightness induction caused by virtual objects, referred to as shadow inducers, which surround the shadow area to gradually amplify the intensity of the real scene pattern [4]. However, because the shadow inducer was prepared beforehand, the shape of the shadow is constant, the real scene shadowing is limited to a flat surface, and a large of viewpoint change is impossible. In this demonstration, we propose a method to generate shadow inducers in real time that can change the shape of virtual objects and the viewpoint of users. In this method, depending on the appearance of shadows, the surrounding luminance is gradually amplified with the difference of gaussian (DOG) representing characteristics of human vision. Users can observe shadows of moving and deforming virtual objects on a real tabletop and other non-planar objects.

This paper proposes a novel method for casting virtual shadows on real surfaces on an optical see-through head-mounted display without any extra physical filter devices. Instead, the method presents shadows as results of brightness induction. To produce brightness induction, we place a texture of the real scene with a certain transparency around the shadow area to amplify the luminance of the surrounding area. To make this amplification unnoticeable, the transparency of the surrounding region is gradually increased as the distance from the shadow region. In the experiment with 23 participants, we confirmed that users tend to perceive the shadow region is darker than a non-shadow area under the conditions where a circular virtual shadow is placed on a flat surface.

Optical See-Through Head-Mounted Displays (OST-HMDs) lose the visibility of virtual contents under bright environment illumination due to their see-through nature. We demonstrate how a liquid crystal (LC) filter attached to an OST-HMD can be used to dynamically increase the perceived brightness of virtual content without impacting the perceived brightness of the real scene. We present a prototype OST-HMD that continuously adjusts the opacity of the LC filter to attenuate the environment light without users becoming aware of the change. Consequently, virtual content appears to be brighter. The proposed approach is evaluated in psychophysical experiments in three scenes, with 16, 31, and 31 participants, respectively. The participants were asked to compare the magnitude of brightness changes of both real and virtual objects, before and after dimming the LC filter over a period of 5, 10, and 20 seconds. The results showed that the participants felt increases in the brightness of virtual objects while they were less conscious of reductions of the real scene luminance. These results provide evidence for the effectiveness of our display design. Our design can be applied to a wide range of OST-HMDs to improve the brightness and hence realism of virtual content in augmented reality applications.

A common factor among current generation optical see-through augmented reality systems is fixed focal distance to virtual content. In this work, we investigate the issue of focus blur, in particular, the blurring caused by simultaneously viewing virtual content and physical objects in the environment at differing focal distances. We examine the application of dynamic sharpening filters as a straight forward, system independent, means for mitigating this effect improving the clarity of defocused AR content. We assess the utility of this method, termed SharpView, by employing an adjustment experiment in which users actively apply varying amounts of sharpening to reduce the perception of blur in AR content. Our experimental results validate the ability of our SharpView model to improve the visual clarity of focus blurred content, with optimal performance at focal differences well suited for near field AR applications.

The ideal AR x-ray vision should enable users to clearly observe and grasp not only occludees, but also occluders. We propose a novel selective visualization method of both occludee and oc-cluder layers with dynamic opacity depending on the user's gaze depth. Using the gaze depth as a trigger to select the layers has a essential advantage over using other gestures or spoken commands in the sense of avoiding collision between user's intentional commands and unintentional actions. Our experiment by a visual paired-comparison task shows that our method has achieved a 20% higher success rate, and significantly reduced 30% of the average task completion time than a non-selective method using a constant and half transparency.

This paper introduces a toolkit with camera calibration, monocular visual Simultaneous Localization and Mapping (vSLAM) and registration with a calibration marker. With the toolkit, users can perform the whole procedure of the ISMAR on-site tracking competition in 2015. Since the source code is designed to be well-structured and highly-readable, users can easily install and modify the toolkit. By providing the toolkit, we encourage beginners to learn tracking techniques and to participate in the competition.

This study addresses the problem of geometric consistency between displayed images and real scenes in augmented reality using a video see-through hand-held display or tablet. To solve this problem, we present approximated user-perspective images rendered by homography transformation of camera images. Homography approximation has major advantages not only in terms of computational costs, but also in the quality of image rendering. However, it can lead to an inconsistency between the real image and virtual objects. This study also introduces a variety of rendering methods for virtual objects and discusses the differences between them. We implemented two prototypes and designed three types of user studies on matching tasks between real scenes and displayed images. We have confirmed that the proposed method works in real time on an off-the-shelf tablet. Our pilot tests show the potential to improve users' visibility, even in real environments, by using our method.

In the study of AR/MR field, tracking and geometric registration methods are very important topics that are actively discussed. Especially, the study on tracking is flourishing and many algorithms are being proposed every year. With this trend in mind, we, the TrakMark WG, had proposed benchmark test schemes for geometric registration and tracking in AR/MR at ISMAR 2009 [1]. This paper is an intermediate report of the TrakMark WG, which describes its activities and the first proposal on benchmarking image sequences.

This paper describes a novel game system which provides multiple players with a sense of touching fire with their own hands. Players in this game are divided into two teams in front of a wall-type flat display and try to score points by grounding a fireball on the other team's court like volleyball. The players can recognize their contacts with the fireball from mirrored image of their own appearance and the superimposed fireball in the display. Computer detects those contacts by using a real-time time-of-flight camera and renders flame of the fireball based on fluid simulation. The reason why we choose fire as a ball is that several characteristics of fire are advantages in interactions between users and virtual objects. This game can provide players with enough enjoyment and reality due to these advantages even if the implemented human detection algorithm is quite simple.

This paper describes a real-time pre-visualization method using augmented reality techniques for videographers. It enables them to test camera work without real actors in a real environment. As a substitute for real actors, virtual ones are superimposed on a live video in real-time according to a real camera motion and an illumination condition. The key technique of this method is real-time motion estimation of a camera, which can be applied to unknown complex environments including natural objects. In our method, geometric and photometric registration problems for such unknown environments are solved to realize the above visualization. A prototype system demonstrates availability of the pre-visualization method.

This paper describes a novel telepresence system that uses high-resolution movies and a reactive display system with a treadmill. In this system, users can walk through a virtualized environment by actually walking on a treadmill. According to walking motion which is detected by using 3-D position sensors put on both legs, the virtualized environment captured by an omnidirectional multi-camera system is projected on a multi-screen display.