Head-attached displays such as retinal displays and video or optical see-through head-mounted displays (HMDs) have been the dominant displays in the early stages of the augmented reality field. Likewise, hand-held displays such as Tablet PCs, personal digital assistants (PDAs), and cellular phones have played an important role as alternatives to mobile augmented reality applications. However, limitations of the conventional displays (head-attached or hand-held displays) such as lack of resolution and small fields of view have led spatially aligned video projectors to be noticeable. In particular, the recent increase in capability and decline in cost have significantly raised the potential of video projectors as a display for augmented reality.
Projection-based augmented reality is a technology that merges the real and virtual worlds by directly projecting virtual information onto 3-D real scenes using video projectors. It enhances user-immersion in the real environment by supporting scalable resolution, large fields of view, and more improved ergonomics. To seamlessly project, the information on everywhere surfaces, however, fundamental problems of projection-based systems should first be resolved. The main purpose of this thesis is to address these problems and provide solutions. This thesis focuses particularly on techniques to compensate projection images that are geometrically and radiometrically distorted on dynamic (or non-planar) and colourful textured surfaces.
Another main purpose of this thesis is to discuss human-computer interaction in projection-based augmented reality systems and introduce an efficient interface using projection-based augmented reality. Until now, projection-based augmented reality has mainly been applied to interactive systems. Interactive tables and walls that are representative have been well suited for collaborative works because they not only provide various visual interfaces on a large interactive space, but also enable users to freely access and share their information with each others without using conventional digital user interfaces such as keyboards or mouse devices. Several researchers in the field of computer aided surgery have also been interested in these off-the-desktop human-computer interactions and have successfully used them to help surgeons to conveniently perform a number of complicated and time-consuming medical operations. In this regard, this thesis proposes a novel projection-based interactive augmented reality system as a case study in computer aided surgery and its validity is shown in experimental results.