Current user interface techniques such as WIMP or the desktop metaphor do not support real world tasks, because the focus of these user interfaces is only on human–computer interactions, not on human–real world interactions. In this paper, we propose a method of building computer augmented environments using a situation-aware portable device. This device, called NaviCam, has the ability to recognize the user’s situation by detecting color-code IDs in real world environments. It displays situation sensitive information by superimposing messages on its video see-through screen. Combination of ID-awareness and portable video-see-through display solves several problems with current ubiquitous computers systems and augmented reality systems.