[attachment=14479]
1. Introduction and Motivation
1.1. Interactive Augmented Reality Interface
Since its inception computer graphics has been interactive in nature. One of the novel aspects of the seminal computer graphics work in Ivan Sutherland’s Sketchpad system (Sutherland 1963) was the ability of a user to interact with the system. A classic text in computer graphics, Newman and Sproull’s Principles of Interactive Computer Graphics, (Newman and Sproull 1973) highlights this interactive nature directly in the title. The creation of interactive virtual environments originated in the computer graphics domain. The ultimate interactive environment is the real world. The goal of augmented reality systems is to combine the interactive real world with an interactive computer-generated world in such a way that they appear as one environment. Figure 1 shows a virtual clock tower placed in a real three-dimensional scene. As the user moves about the real scene and views it from different viewpoints, the image of the clock tower is continually updated so that it is perceived as a real object in the scene. This verisimilitude carries through to human interactions with the virtual object such as moving or lifting it, and the object’s interaction with real objects, such as collisions.
1.2 The Major Challenges for Augmented Reality Systems
The major challenge for augmented reality systems is how to combine the real world and virtual world into a single augmented environment. To maintain the user’sillusion that the virtual objects are indeed part of the real world requires a consistent registration of the virtual world with the real world.
These relationships are the object-to-world, O, world-to-camera, C, and camera-to image plane, P, transforms (Figure 2). The object-to-world transform specifies the position and orientation of a virtual object with respect to the world coordinate system that defines the real scene. The world-to-camera transform defines the pose of the video camera that views the real scene. Finally, the camera-to-image plane transform specifies the projection the camera performs to create a 2D image of the 3D real scene.