The document is a lecture introduction by Dr. Ebtehal Galal, which covers the physics of light and various aspects of lighting including natural and artificial sources. It discusses the importance of light in architecture, vision, and human perception, emphasizing the need for appropriate lighting conditions for visual tasks. Key factors affecting visibility such as age, size, contrast, and luminance are also addressed.

1. Lecture 1
General Introduction
By Dr. Ebtehal Galal 2017

2. Physics
of light
Natural
lighting
Artificial
lighting
Lighting

3. • Ch 1: Visual and Perception
• Ch 2: Properties of Light
• Ch 3: Natural Light in Buildings
• Ch 4: Electric Light
• Ch 5: Light and Form
• Ch 6: Lighting Calculation
Methods
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For the most part of the history of mankind, there were
basically two sources of light available.
the other is flame.The older one of these two is daylight,

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• Oil
• Chimney
• Candle light
• Al Razzi
kerosene lamp
900 ce
• 1000 first street
lamp in
Andalusia
• Gas
• Use petroleum
instead of gas
• Using filament
• 1879‫م‬
Adison
electric lamp

7. Types of light sources
Light
source
Natural Artificial
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this meant adapting architecture to the requirements for lighting
with natural light.

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12. Vision, biological needs,
visual information.

13. • Good visual environments allow us to focus
on what we want to see.
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1. Nonuniform lighting
layouts with no glare
2. Focusing on walls
rather than overhead
lighting
1. Openings to allow
daylight penetration
2. Avoidance of visual
noise from solar shading
devices
3. Respect privacy
needs at ground-level
openings
William Lam has identified many of these biological information needs
such as:

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Most of the information we receive about the world
around us is through our eyes.
Binocular vision.
The ability of the brain to perceive the images from both eyes
as a single image

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Complicated proces
between eye and
brain..
-1-forming the image
-2-Transfer the image
through optic nerve to
the brain
-3-perceive the images
“perception”: enables
recognition and
understanding to
images,

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Experience,
expectations,
lighting, and emotion
influence perception
or evaluation of
visual images.

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Motion perception

19. • The binocular visual field extends vertically 130° and horizontally
more than 120° when both eyes are focused on a fixed object.
Vision by one eye alone is called monocular vision.
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Visual task performance generally involves
- Detection (I see something),
- Recognition (it is a man),
- and Identification (the man is Mohamed).
What is visual tasks?

21. • As the visual task becomes more
demanding, the lighting conditions become
increasingly critical.
• When the tasks are specific to a location, the
designer can provide an appropriate quality
and quantity of light for that task.
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22. there are many factors affect visibility such
as: visibility α size

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Illuminanation 1/α size

24. • visibility α age
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Visual performance decreases from the late twenties on, because of
yellowing of the lens and other factors
As age increases, normal-sighted persons need a higher illumination level'
and optimum contrast of visual tasks to achieve best visual performance

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This is an important consideration in the illumination of exit signs for
visibility under emergency conditions in smoke-filled rooms.
• visibility α contrast

26. • visibility α time available to perform a task
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Visual acuity improves with increasing
duration of exposure
increased luminance can solve the
missing of suitable duration .

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29. • visibility α luminance of visual field
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Our speed of reading is already
nearly 80 percent of our maximum
ability;
increasing the task luminance to 30
cd/ft2) provides about a 10 percent
additional increase.

30. • visibility α size
• Illuminanation 1/α size
• visibility α age
• visibility α contrast
• visibility α time available to perform a task
• visibility α luminance of visual field
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