3D Object Manipulation Techniques in Handheld Mobile Augmented Reality Interface: A Review <s> I. INTRODUCTION <s> Paul Milgram received the B.A.Sc. degree from the University of Toronto in 1970, the M.S.E.E. degree from the Technion (Israel) in 1973 and the Ph.D. degree from the University of Toronto in 1980. From 1980 to 1982 he was a ZWO Visiting Scientist and a NATO Postdoctoral in the Netherlands, researching automobile driving behaviour. From 1982 to 1984 he was a Senior Research Engineer in Human Engineering at the National Aerospace Laboratory (NLR) in Amsterdam, where his work involved the modelling of aircraft flight crew activity, advanced display concepts and control loops with human operators in space teleoperation. Since 1986 he has worked at the Industrial Engineering Department of the University of Toronto, where he is currently an Associate Professor and Coordinator of the Human Factors Engineering group. He is also cross appointed to the Department of Psychology. In 1993-94 he was an invited researcher at the ATR Communication Systems Research Laboratories, in Kyoto, Japan. His research interests include display and control issues in telerobotics and virtual environments, stereoscopic video and computer graphics, cognitive engineering, and human factors issues in medicine. He is also President of Translucent Technologies, a company which produces "Plato" liquid crystal visual occlusion spectacles (of which he is the inventor), for visual and psychomotor research. <s> BIB001 </s> 3D Object Manipulation Techniques in Handheld Mobile Augmented Reality Interface: A Review <s> I. INTRODUCTION <s> This paper surveys the field of augmented reality AR, in which 3D virtual objects are integrated into a 3D real environment in real time. It describes the medical, manufacturing, visualization, path planning, entertainment, and military applications that have been explored. This paper describes the characteristics of augmented reality systems, including a detailed discussion of the tradeoffs between optical and video blending approaches. Registration and sensing errors are two of the biggest problems in building effective augmented reality systems, so this paper summarizes current efforts to overcome these problems. Future directions and areas requiring further research are discussed. This survey provides a starting point for anyone interested in researching or using augmented reality. <s> BIB002 </s> 3D Object Manipulation Techniques in Handheld Mobile Augmented Reality Interface: A Review <s> I. INTRODUCTION <s> In 1997, Azuma published a survey on augmented reality (AR). Our goal is to complement, rather than replace, the original survey by presenting representative examples of the new advances. We refer one to the original survey for descriptions of potential applications (such as medical visualization, maintenance and repair of complex equipment, annotation, and path planning); summaries of AR system characteristics (such as the advantages and disadvantages of optical and video approaches to blending virtual and real, problems in display focus and contrast, and system portability); and an introduction to the crucial problem of registration, including sources of registration error and error-reduction strategies. <s> BIB003 </s> 3D Object Manipulation Techniques in Handheld Mobile Augmented Reality Interface: A Review <s> I. INTRODUCTION <s> We are on the verge of ubiquitously adopting Augmented Reality (AR) technologies to enhance our percep- tion and help us see, hear, and feel our environments in new and enriched ways. AR will support us in fields such as education, maintenance, design and reconnaissance, to name but a few. This paper describes the field of AR, including a brief definition and development history, the enabling technologies and their characteristics. It surveys the state of the art by reviewing some recent applications of AR technology as well as some known limitations regarding human factors in the use of AR systems that developers will need to overcome. <s> BIB004
According to Milgram and Kishino BIB001 , augmented reality (AR) refers to all cases in which the display of an otherwise real environment is augmented by means of virtual (computer graphic) objects. Extended from this definition, Azuma BIB002 defined that AR is the variation of virtual environments or virtual reality; however, unlike virtual reality that immerses a user inside a synthetic environment and the user cannot see the real world around him/her, AR allows the user to see the real world, with virtual objects composited with the real world. Beyond that, some researchers have done The associate editor coordinating the review of this manuscript and approving it for publication was Waleed Alsabhan. a number of surveys or reviews about AR. For example, Krevelen and Poelman BIB004 , drawing up conclusions from several previous works, defined the AR system as: 1) combining real and virtual objects in a real environment; 2) registering real and virtual objects with each other and 3) running interactively, in 3D and in real-time. From another point of view, Mekni and Lemieux  proposed to define AR as systems that have the following characteristics: 1) combining real and virtual content; 2) interactive in real time and 3) registered in 3D. Thus, conclusions from the above statements provide a commonly accepted definition of AR as a technology which: 1) combines real and virtual imagery; 2) is interactive in realtime and 3) registers the virtual imagery with the real world FIGURE 1. Timeline of the researches related to interaction techniques for 3D object manipulation in the AR system. Researches related to handheld mobile AR that stated with their related technique categories are colored in red. in 3 dimensions (3D). However, do not limit the potential of AR technology in different aspects, the current definition may be modified based on different cases and different conditions; for example, AR should not be limited to particular display technologies which only focus on our sense of sight, and AR can be potentially applicable to all senses, including hearing, touch and even smell BIB003 . Although there are several definitions of AR, interaction is still the keyword and the main concept in this context.