Chapter 5: Brightness Flashcards
The intensity of light falling on a given region of the retina at a certain time is a result of?
Brightness
The intensity of light that the retina has been subject to in the recent past is a result of?
Brightness
The intensities of light falling on other regions of the retina is a result of?
Brightness
We quantify light as?
Lumens
Lumens of light striking a surface will cause?
Illuminance
Illuminance is expressed in?
Foot-candles
Light that is reflected from a surface ina given direction back toward the eyes is defined as?
Luminance
Lumens of light leaving a surface generally = ___
Exitance
____ is light leaving
Exitance
Exitance is measured in?
lm/ft^2
Luminance is most closely related to the assessment of “____”
Brightness
How is luminance measured?
cd/ft^2
we talk about illuminance “___” a surface
Onto
we talk about the exitance “__” or “___” a surface
of; from
we talk about the luminance “_” or “__” a surface
of; from
____ is light leaving in a specific density as viewed from a specific vantage point
Luminance
What are the 3 interactions of light?
Light Source; Viewer; Reflective Surface
___ is the sensation produced by an extreme illuminance within the normal field of view that is sufficiently greater than the luminance to which the eyes are adapted
Glare or Reflected Glare
____ _____ is the degree of visual satisfaction produced by the luminous environment, resulting from the reduction of glare and distracting illuminance in the field of view
Visual Comfort
VCP stands for?
Visual Comfort Probability
a VCP < ___-___ is not recommended for general office
70-80
Luminares emit light (lumens) in one of 3 directions. What are they?
Downward; Upward; Multidirectional
These are all examples of the 7 different ____/_____ types
1. Concentrated Downward(Direct)
2. Diffused Downward(Direct)
3. Concentrated Upward (Indirect)
4. Diffuse Upward (Indirect)
5. Multidirectional Concentrated (Semi Direct or Semi Indirect per amount of light going up or down)
6. Direct/Indirect
7. Multidriectional Diffuse (General Diffuse)
Direction/distribution types
___ ___ = sunlight casting shadows and modeling shapes
Direct Light
___ ___= softens the shadows and fills the voids
Indirect Light
____ results from the intensity of light that intially strikes a surface and the reflecting or transmitting properties of that surface
Brightness
Darl/ low reflectance surfaces ____ light
Absorb
Light colored, highly reflective finishes ___ much more light
reflect
These are all examples of how to ___ ____
1. Limit the amount of light emitted in the direction of the eye
2. Increase the area from which the light is emitted
3. Direct the light away from the main visual field
Reduce Glare
______ is an archaic term used to quantify reflected light
Footlamberts
What is Grazing light?
When you want to illuminate a textured wall
What is Acuity
The ability of an eye to focus
what is the difference between direct glare and indirect glare?
Direct glare is right into the eye. Indirect light is a reflection of light off something (such as a computer screen) into the eye.
