28 Critical Reflections: random 1 t0 7

The term specular means that light is perfectly reflected in a mirror-like way from the light source to the viewer. Specular reflection is visible only where the surface normal is oriented precisely halfway between the direction of incoming light and the direction of the viewer; this is called the half-angle direction because it bisects (divides into halves) the angle between the incoming light and the viewer. Thus, a specularly reflecting surface would show a specular highlight as the perfectly sharp reflected image of a light source. However, many shiny objects show blurred specular highlights.[6]

This can be explained by the existence of microfacets. We assume that surfaces that are not perfectly smooth are composed of many very tiny facets, each of which is a perfect specular reflector. These microfacets have normals that are distributed about the normal of the approximating smooth surface. The degree to which microfacet normals differ from the smooth surface normal is determined by the roughness of the surface. At points on the object where the smooth normal is close to the half-angle direction, many of the microfacets point in the half-angle direction and so the specular highlight is bright. As one moves away from the center of the highlight, the smooth normal and the half-angle direction get farther apart; the number of microfacets oriented in the half-angle direction falls, and so the intensity of the highlight falls off to zero.[6]

So, anyway, the people. Their clothes were shiny too, but lots of different colours. Skin-tight. They wore helmets with stubby aerials, and goggles. But the goggles had lines of information flickering across them.[2]

But the first thing to make clear is that a specular reflection cannot be taken as a sign if one follows the definition given in this book. Not only can it not be properly called an image (since it is a virtual image, and therefore not a material expression) but even granted the existence of the image it must be admitted that it does not stand for something else:on the contrary it stands in front of something else, it exists not instead of but because of the presence of that something: when that something disappears the pseudo-image in the mirror disappears too.[3]

There is an inside and an outside to every form. When they are in special accord, as for instance a nut in its shell or a child in the womb, or in the structure of shells or crystals, or when one senses the architecture of bones in the human figure, then I am most drawn to the effect of light. Every shadow cast by the sun from an ever-varying angle reveals the harmony of the inside to outside.[7]

Carving is interrelated masses conveying an emotion; a perfect relationship between the mind and the colour, light and weight which is the stone, made by the hand which feels. It must be so essentially sculpture that it can exist in no other way, something completely the right size but which has growth, something still and yet having movement, so very quiet and yet with a real vitality.[7]

The term specular means that light is perfectly reflected in a mirror-like way from the light source to the viewer. Specular reflection is visible only where the surface normal is oriented precisely halfway between the direction of incoming light and the direction of the viewer; this is called the half-angle direction because it bisects (divides into halves) the angle between the incoming light and the viewer. Thus, a specularly reflecting surface would show a specular highlight as the perfectly sharp reflected image of a light source. However, many shiny objects show blurred specular highlights.[6]

28 Critical Reflections random 8 to 14
Back to Clive's home page

Sources

[1] http://www.neworleanspast.com/art/id62.html

[2] Ken MacLeod, Reflective Surfaces, New Scientist, 2009.

[3] Umberto Eco, A Theory of Semiotics, Indiana University Press, 1979.

[4] Clive Fencott, Reflections on seeing River Form in Barbra Hepworth's garden in St. Ives.

[5] http://www.flickr.com/photos/nigelhomer/316548379/

[6] http://en.wikipedia.org/wiki/Specular_highlight

[7] http://www.barbarahepworth.org.uk/texts/

[8] tripadvisor.co.uk