Raffles Institute_Perception of light and Photometric Character
ENVIRONMENTAL LIGHTINGTERM: JUNE 2013LECTURER: SANDRA DRASKOVICPECEPTION OF LIGHTLIGHTPHOTOMETRIC CHARACTERISTICDAYLIGHT
Light is not so much somethingthat reveals, as it is itself therevelation.James Turrell
Rudolf Arnheim (1974),“But the prevailing view throughout the worldseems to have been and to be that light,although originally born from primordialdarkness, is an inherent virtue of the sky, theearth, and the objects that populate them, andthat their brightness is periodically hidden orextinguished by darkness” (p.304)
LITERATURE AND READINGS1. Rudolf Arnheim, Art and Visual Perception: A Psychology of the Creative Eye.Berkeley and Los Angeles: University of California Press.2. Rudolf Arnheim, Visual Thinking. Berkeley: University of California Press.3. Rudolf Arnheim, The Dynamics of Architectural Form. Berkeley and LosAngeles: University of California Press.4. Interior lighting for designers, Gary Gordon5. Raffles International institute, Text book6. Magazines and periodicals
Visible lightWhat we perceive is narrow band of electromagneticenergy, ranging from 380nm to 760 nm. Physicaldifference between radio waves, infrared, visible light,ultraviolet and x-rays is their wavelength.
Light reflection, absorption and refraction•In perfect vacuum light travels aprox 186.000 milesper second. When light moves through space it hasstraight line till it hits some object. Depending onwhat it hits, light may behave in many different ways.•When light travels through glass or water it slowsdown significantly depending on the velocity anddensity of the material.•Reflection – when light bounce back on objects•Absorbtion – depending on the surface, some part oflight is absorbed by the surface, and light energy istransformed into heat energy•Refraction – when light is being transmitted throughmaterial and pass through
Eye perception and visionHuman eye gather information from outside world. Itsfocusing lens throws inverted image onto a densemosaic of light-sensitive receptors, which convert thepattern of light energy into chain of electricalimpulses that the brain will interpret.
Eye perception and visionThe human visual system has:1. a structure that collects environmental stimuli(eye)2. receptors that transform environmental energyinto neural code (rods and cones)3. neurons transmitting signals towards the brain(optic nerve, LGN)4. central neurons generating perceptualexperienceBrain interprets available data that are transmittedby optical neurons from eyes. The perception ishypothesis, suggested and tested by sensory
Characteristics of light1.Luminous flux2.Luminous intensity3.Illuminance4.Luminance5.Contrast
1. Luminous flux• In photometry, luminous flux or luminous power isthe measure of the perceived power of light.• It differs from radiant flux, the measure of the totalpower of light emitted, in that luminous flux isadjusted to reflect the varying sensitivity of thehuman eye to different wavelengths of light.• unit of luminous flux is the lumen (lm). One lumenis defined as the luminous flux of light produced bya light source that emits one candela of luminousintensity over a solid angle of one steradian.
2. Luminous intensity• luminous intensity is a measure of the wavelength-weighted power emitted by a light source in aparticular direction per unit solid angle, based onthe luminosity function, a standardized model ofthe sensitivity of the human eye.• The SI unit of luminous intensity is the candela(cd)• Luminous intensity should not be confused withanother photometric unit, luminous flux, which isthe total perceived power emitted in all directions.Luminous intensity is the perceived power per unitsolid angle.
3. Illuminance• The illuminance or light level is the amount of lightenergy reaching a given point on a defined surfacearea, namely the luminous flux (i.e. lumens) persquare meter.• It is a measure of how much the light illuminatesthe surface, wavelength-weighted by theluminosity function to correlate with humanbrightness perception.• In SI derived units these are measured in lux (lx)or lumens per square meter.
4. Luminance• Luminance is the amount of light energy emitted orreflected from an object in a specific direction.• Luminance is the only form of light we can see.Luminance is the unit which relates to theperceived brightness of a given object.• Luminance is measured in candela per squaremeter (cd/m2) or nit. 1 nit is defined as theluminance of a purely white object being exposedto a light level of p lux.
Brightness• Brightness is an attribute of visual perception in whicha source appears to be radiating or reflecting light. Inother words, brightness is the perception elicited bythe luminance of a visual target.• brightness, in physics, the subjective visual sensationrelated to the intensity of light emanating from asurface or from a point source.• Brightness refers to how much light energy isreflected by the surface and depends on the colorvalue, material nature and texture. Shiny light colorsurface will reflect more light than matte dark ortextured surface.• Control: Diffusing and controlling light distribution.
Glare• Glare is difficulty seeing in the presence of bright lightsuch as direct or reflected sunlight or artificial lightsuch as car headlamps at night. Because of this,some cars include mirrors with automatic anti-glarefunctions.• Glare can be generally divided into two types,discomfort glare (direct) and disability glare (indirect).Discomfort glare results in an instinctive desire tolook away from a bright light source or difficulty inseeing a task. Disability glare impairs the vision ofobjects without necessarily causing discomfort.• Control: Reduction in contrast of the rest of the sceneand using light shielder.
Glare and brightness control1. Diffuser – upward, downward, concentrated2. Shield and barrier – light control techniques
Veiling reflection• Reflected Glare or Veiling Reflection is a reflection ofincident light that partially or totally obscures thedetails to be seen on a surface by reducing thecontrast.
5. Contrast• Contrast refers to the differences betweenluminances and is used as a factor or a ratio. Thehighest contrast ratio obtainable is the ratiobetween maximum and minimum luminance in animage. In plain language, it’s the differencebetween the maximum white and (minimum) blackluminance level, expressed as a ratio between thetwo.• To measure the contrast ratio, the nit values of thebrightest and the darkest parts of an image shouldbe measured.
Medieval ageLet there be light. The use of shadows and light isrelated to presentation of religious motives andhighlighting the importance of the divine subjectpresented. The art got more realistic by usingshadows and light.
Lighting includes the use of bothartificial light sources like lamps andlight fixtures, as well as naturalillumination by capturing daylight.
DaylightDaylight or the light of day is the combination of alldirect and indirect sunlight outdoors during thedaytime. This includes direct sunlight, diffuse skyradiation, and (often) both of these reflected from theEarth and terrestrial objects.Designers shall provide an internal space withdaylight from both direct and indirect sources.
Daylight1. Sunlight - direct light from the Sun, total spectrumof electromagnetic radiation give by the Sun.Impractical and usually shielded and controlled.1. Skylight – the light from the sky. Reflected anddiffused by air molecules. Sunlight foltred byatmosphereRequires special building configuration andnecessary control for horizontal surfaces.1. Ground light – sunlight or skylight reflected by thesurface bellow the plane of horizon
Daylight1. People require visual stimuli and constant changesBiological and psychological need for moderate change2. Comfort requires moderate stimulation to providesemotional appeal but override visual overstimulation3. Size, shape, position and design of theopening/fenestration affect the quality of daylight andtransition between inside and outside:- windows- skylight- shaded skylight, flat skylight, clerestories, sawtooth- louvers, brise soleil and shades
Steven Holl• Characteristics of his projects - preoccupation withlight and color as ways to inform the shaping of space.Holl’s architecture has consistently defined itself withformal gestures grounded in light and meaningfulapplications of textures and colors.• Space is oblivion without light. A building speaksthrough the silence of perception orchestrated by light.Luminosity is as integral to its spatial experience asporosity is integral to urban experience.
art show, Hayward gallery, LondonFeaturing 25 illuminated installations andsculptures by major international artists from the1960s to the present; all exploring the medium oflight and how it responds to the surroundingarchitecture.Throughout history, artists have been fascinated bylight and its nature, behavior and peculiarities. but itis only in the last hundred years that actual lighthas become a medium for art. in the first half of thetwentieth century, with the development oftechnology and increasing questioning of traditionalart forms, artists began to experiment with thevisual and sensory effects of artificial light.
our uncertain shadow (colour)comprises halogen lamps with variously coloredbulbs on the floor and a white projection screen; asyou walk across the room, your moving shadow isprojected in a combination of flickering colors.“A row of small, bright spotlights in several colorslined up along one wall of an empty room. That’sall. Museum visitors who enter the room castmultiple shadows of varying color, darkness, andsize, depending on their position, against the blankopposite wall.
Cylinder II by Leo Villareala spectacular cylinder of light made up of 19,600computer-controlled LEDs and an installation whichreceives its first showing in the UK.Its cylindrical form is at once dense and ephemeral,as it shimmers and oscillates between dimensions.Controlled by software code that the artist developedover an extensive period of time, like a composerworking over a score, the nodes cycle through aseemingly infinite series of patterns and movements,fast and slow, bright and dark.
Jenny Holzer’s Monumentlooks at the use of light and language in advertisingwith this display of U.S. government documents,using semicircular electronic LED signs.Using LED technology, sculpture, light projectionpieces, and groupings of new paintings ofgovernment documents made available through theFreedom of Information Act. Holzer chooses existingtexts from sources ranging from these officialdocuments to poetry and literature to her own earlierseries.
Conrad Shawcrossfrequently refers to celestial light and its associatedsciences in his work. Here, Slow Arc Inside A CubeIV uses a motor to throw a dizzying spectacle of lighton ceiling, floor and walls.Explains that though he has always made works withlight and movement, he was never very interested inshadows until he read hodgkin’s description of theprocess of examining the diffraction pattern of X-raysbounced off the protein’s atoms, which shecompared to decoding the shape of a tree from theshadows cast by its leaves
Carlos Cruz-Diez, Chromosaturationcreates ‘a space where colour acts with all its forceon the spectator’s skin, objects and surrounding wallsurfaces.’ in his view, colour does not consist ofpigment on a solid surface, but is a ‘situation’ causedby the projection of light on objects, and the way inwhich this light is perceived by the human eye. as heexplains, ‘the Chromosaturation is an artificialenvironment composed of three colour chambers,one red, one green and one blue that immerse thevisitor in a completely monochrome situation.
Ann Veronica Janssens, Rosecreates immersive sensory installations, usingdevices such as light, artificial fog, colour projections,mirrors, reflective materials and sound in order topush human perception to its limits. she describesthe space-time experiences at the heart of her workas being close to altered states of consciousnesssuch as those produced under the influence of adrug or hypnosis.
Holes of Light,Nancy Holtin her large-scale outdoor works, nancy holt’sparticular concerns are to make people more awareof light, space and time and their own visualperception. her interventions into natural and man-made landscape involve the use of ‘locators’ – holesand tunnels – to channel the viewer’s vision andframe a particular view. here, in one of her fewindoor installations, Holes of Light, she plays with theindeterminacy of light and variable viewing positions.the mechanics of the work consist of two brilliantlamps mounted on opposite walls of a space dividedby a thin central partition perforated with a diagonalline of large circular holes.
cerith wyn evans,S=U=P=E=R=S=T=R=U=C=T=U=R=Egenerated by the columns’ lamps, reflects theunearthliness of the text that forms the other,parenthetical, part of its title: (‘Trace me back tosome loud, shallow, chill, underlying motive’soverspill…’). this invocation is taken from JamesMerrill’s epic poem The Changing Light at Sandover.columns are made from obsolete incandescent striplights. columns are not all exactly the same size,their positioning affects the way that the viewerreads the space they are in, and the way it isarticulated.