The Digital Chameleon Principle : Computing Invisibility

H ow many of us have had a dream of being invisible? But is that really that far-fetched, impossible, or improbable? As a child I used to daydream of magical powers that let me pursue exciting adventures in magical wonderlands. These great magical powers exhibited technology far beyond the current state of the art. I still clearly remember today those fantastic dreams. Indeed, dreaming that kind of fantasy let me feel good and relaxed, and they certainly colored my childhood. I personally think that daydreaming is also a kind of healing therapy of our day-to-day busy life to satisfy our curiosity. However, nowadays I also feel somewhat more conservative (and do not dream unfortunately anymore of Harry Potter worlds), partly because of my science background gained over the last 20 years or so of school education. School taught me the way to reasonably and rationally think without leaving much space for extravagance. That phenomenon is what Sir Arthur C. Clarke called the failure of the nerves in his book Profiles of the Future: An Inquiry into the Limits of the Possible. A good example cited by Clarke are excerpts of scholarly articles written by experts claiming the then impossibility of heavier-thanair flying machines. Nowadays, we all take airplanes, so why do children still dream of magical worlds? Maybe, a simple answer is that children use and look at technology without fully understanding their underlying mechanisms making it possible. It’s easier for them to naturally extend the scope of those technologies according to their will. In this article, I will examine the concept of invisibility in detail with a good flavor of computer graphics. But first, let me quickly review its historical background.