Lighting : Lighting October 2016 - Vol 36 Issue 5
6 LIGHTING MAGAZINE | October/November 2016 FROM THE EDITOR Earlier in the year I was staying in a hotel in Bangkok and part of the view from the balcony is shown in the photograph below. It looks like a carpark but there seems to be a tentlike frame running from the lower left hand side to the middle of the right hand side. A little higher, towards the upper left there seems to be a fence of white posts with a black and white rail along the top. But you know there is something wrong, since you know that it is a carpark, with angled parking. There are two sets of white road markings – an older, less bright set at right angles to the lanes and a newer, brighter set at about 30̊ to the lanes. This creates the illusion that the brighter ones are above the carpark surface where they meet on the painted line running from roughly left to right, creating the tentlike frame. The black and white fence-top is a curb but it also appears to be elevated, as though it is sitting atop posts that are actually the parking spaces painted on the carpark surface. The illusion occurs because the older, 90̊ parking markings were not removed when the parking arrangement was changed. The visual system, in trying to make sense of all the white lines and other cues, flips between the two options of angled and 90̊ parking to create a three dimensional interpretation of the lines, with the newer ones being raised where they meet. Similarly, the sloping lines that meet the black and white curb are parallel to the white fence posts (of the obvious fence) creating the illusion of another fence. The strengths of the illusions is a matter of chance, probably due to the height at which I viewed the carpark and my viewing position that meant that some horizontal lines appeared to be parallel to some vertical lines. At ground level the illusions would probably not be apparent or not as strong. However, I think it is a good illustration of the essence of seeing; that is to give meaning to the patterns of light detected by our eyes and interpreted by our brains to give meaning, literally to see. In this case there is confusion between what we know to be true (a carpark) and what could be true (a fence and a white frame). Eventually, we dismiss the “could be” case and settle on the “true” case. It is possible to create confusing illusions using light, particularly by the creation of shadows and highlights in as scene. These can be unintended and can create confusion and the potential for accidents. The most common dangerous illusions are those concerning changes of level, as on stairs. We use experience as we negotiate the real world, often relying upon our imprecise and somewhat fuzzy view of the world we see in peripheral vision. Or if you have low vision, you will always have a fuzzy view of the environment. So, if you don’t see a step or anticipate one that isn’t really there your body will be out of balance and the result could be a stumble or, worse, a fall. Designers need to be alert to these risks; especially where the only contrasts in a scene are being created using light rather than surface finishes. Illusions can be fun or catastrophic. I hope that you will find this issue illusion-free but nevertheless enjoyable. Warren Julian Editor What’s real and what’s not?
Lighting August 2016 - Vol 36 Issue 4
Lighting December 2016