omputing is an integral part of our daily routines. However, despite numerous technological advances, how we interact with computers has changed little in the past three decades. Current systems use conventional input devices, such as a mouse, that limit functionality and often require applications to define a complex, nonintuitive interaction language. In this new age of human-centered computing, humancomputer interaction (HCI) must look to new technologies for building modern, natural, and intuitive interfaces. Video is one such technology. Computer vision techniques could provide far richer interactivity than conventional devices. With the video input signal, systems could use large-scale, unencumbered motion from multiple concurrent users leading to more direct, robust, and effective computing. Using video in HCI is difficult, as evidenced by the absence of video-based interaction systems in production. Some research systems exist, however, as the "Examples of Video-Based HCI" sidebar describes. 1,2 The visual interaction cues (VICs) paradigm uses a shared perceptual space between the user and the computer. In the shared space, the computer monitors the environment for sequences of expected user activity at locations corresponding to interface components. Approaching the problem this way removes the need to globally track and model the user. Instead, the system models the sequence of localized visual cues that correspond to the user interacting with various interface elements. The 4D Touchpad is a video-based computing platform based on the VICs paradigm. Together, the VICs paradigm and the 4DT provide a rich new set of techniques that bring the human to the center of HCI design and surpass some restrictions of conventional interface technology. VICs InteraCtIon model An interaction model is a set of principles, rules, and properties guiding an interface's design. 3 The model describes how to combine interaction techniques both meaningfully and consistently and defines the interaction's look and feel from the user's perspective. The current windows, icons, menus, and pointers (WIMP) 4 interface technology is a realization of the direct manipulation interaction model. 5 The four principles of direct manipulation are new technologies that use multimodal input, human experience, and modern hardware's full computational power could mitigate current limitations in human-computer interaction. the 4d touchpad, a video-based interaction platform, makes robust, natural interaction between humans and computers possible.
