Light and Vision in Design
Light and the Electromagnetic Spectrum
Light is part of the electromagnetic spectrum, which includes a wide range of waves, from cosmic rays to gamma rays, ultraviolet rays, and more. Each type of wave occupies a specific range within the spectrum, defined by its characteristic wavelength or frequency.
Properties of Light
Reflection
Reflection occurs when light strikes a surface separating two different media. The law of reflection governs this phenomenon, stating that the angle of incidence (the angle at which light hits the surface) is equal to the angle of reflection (the angle at which light bounces off the surface). The type of surface determines the direction of reflected light.
Refraction
Refraction occurs when light passes from one medium to another, causing the light to bend. This bending happens because the speed of light changes as it travels through different media. The law of refraction governs this phenomenon.
Transmission
Transmission refers to the passage of light through a medium. Double refraction is a specific type of transmission where light splits into two rays when passing through certain materials.
Absorption
Absorption is the process by which a material absorbs light energy. This process is closely linked to color perception. The human eye is only sensitive to a small portion of the electromagnetic spectrum, which we perceive as colors. When light hits an object, some wavelengths are absorbed, while others are reflected. The reflected wavelengths determine the color we see.
Vision and Light
Quantity of Light
The amount of light, or illuminance, significantly impacts vision. We experience different types of vision depending on the light level:
- Photopic Vision: Occurs in bright light, providing sharp and detailed color vision.
- Scotopic Vision: Occurs in low light, with reduced color perception and sensitivity. Vision becomes more sensitive to blue light at this level.
- Mesopic Vision: Represents an intermediate state between photopic and scotopic vision. As light levels decrease, our ability to distinguish colors diminishes, and sensitivity shifts from yellow to blue.
Accommodation
Accommodation is the eye’s ability to adjust its focus automatically based on the distance of an object. This process allows us to see clearly at varying distances.
Adaptation
Adaptation refers to the eye’s ability to adjust to changing light levels. This involves regulating the pupil’s size, retinal sensitivity, and photochemical changes in the retina.
Visual Field
The visual field is the area we can see without moving our eyes. Monocular vision refers to the visual field of a single eye, while binocular vision encompasses the overlapping area of both eyes, providing depth perception. The typical human binocular visual field spans approximately 180 degrees.
Factors Affecting Vision
Vision can be influenced by both external and internal factors:
- Subjective Factors: These relate to an individual’s visual health, attention level, fatigue, motion, and overall visual comfort.
- Objective Factors: These include the size of the object being viewed, visual acuity, contrast, and viewing time.
Color Perception
Color perception involves both a physical phenomenon (light and its interaction with objects) and a sensory phenomenon (how our eyes and brain interpret light signals).
Color as a Physical Phenomenon
White light, like sunlight, comprises a spectrum of colors. When white light illuminates an object, the object absorbs some wavelengths and reflects others. The reflected wavelengths determine the color we perceive. Using a monochromatic light source or a discontinuous spectrum can distort color perception.
Color as a Sensory Phenomenon
We perceive colors as warm (yellow, orange, red, light green) or cool (violet, blue, dark green) based on their psychological effects and associations.
Color Mixing
- Primary Colors: Cyan, magenta, and yellow are primary colors because their combinations can create all other colors.
- Secondary Colors: Mixing two primary colors in equal proportions produces secondary colors.
- Tertiary Colors: Mixing a primary color with an adjacent secondary color creates tertiary colors.
There are two main types of color mixing:
- Additive Color Mixing: Involves combining colored light beams. The resulting color depends on the proportion of each component color. Combining complementary colors in equal amounts theoretically produces white light.
- Subtractive Color Mixing: Occurs when white light passes through a series of color filters. Each filter absorbs specific wavelengths, resulting in a color with an intensity between the component colors.
Systems like the Munsell color system and the RGB color model provide standardized ways to define and represent colors.
Lighting Techniques in Graphics
Polar Pattern or Light Distribution Curve
: intensity is represented by a three coordenadas.I numerical value of the luminous intensity in candelas and indicates the length of the vector while others point the direction. angle C in that vertical plane and Y are measured about the vertical axis inclination of lumninaria. in the curve radii and the circumference represent concentric anguloY value ls intensity of candles.
-Matrix light intensities: for each pair of values c and I get a value for a standard lamp flux 100lm
-Diagram isocandela (will represent a plane by curavs level, points of equal value in light intensity. Each dot indicates a direction of an area defined by angular coordinates. Distinguish two cases: projectors for projection and lighting fixtures for lighting Lambert azimuthal publico.Proyeccion.
-Curves isolux: refer to illuminance. give information about the amount of light received at each point on the surface of tarbajo and are used for street lighting. They are expressed in absolute values defined for a 1000 lm lamp and mounting height of 1m.