In the early 19th century, panoramas were the state of the art immersive attractions to exhibit huge landscapes. The public had the possibility to look in any direction and had the really feeling of being somewhere else. Then came panoramic cinemas and, what we call now, immersive devices with real-time CG content. To get the feeling of being emerged there are three necessary steps: wrapping, saturation, and participation. If be immersed is so fascinating, it is because it always activates a situation of transgression. Dealing with those questions drives us to reconsider the definition of the concept ‘ambiance’ by comparing processes involved in immersion, storytelling, and architecture. For us, ‘ambiance’ refers to a potential that is activated by a story in a defocusing process.