Light & Vision
Last Update: November 10, 2011
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Helping People to See

No lighting system can create ideal seeing conditions for all people at all times, for all tasks and for all directions of view. Typical design approaches for indoor and outdoor lighting have evolved over time, and successful approaches ensure good seeing conditions for a range of typical visual tasks in that environment.

This section introduces three ways in which lighting systems can help people to function more effectively and more safely:

  • By illuminating critical objects well.
  • By avoiding glare and reflections that obscure tasks.
  • By allowing people to adapt their lit environment to optimize vision.

In general, a successful visual environment will be glare- and flicker-free, it will have adequate contrasts between one object and another, and subtle gradations of tone to reveal shape. However, people’s visual needs and preferences vary widely, due to ageing, disease, and simple variation between one person and another. For this reason, although there are general rules about what constitutes “good lighting”, it is equally important to allow people some flexibility to switch lights on or off, or to move them around to suit their personal needs.

Illuminating Critical Objects
There are usually a small number of critical objects in a space that define how that space is perceived, or how well a task can be performed.  These critical objects can be two-dimensional or three-dimensional.
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Avoiding Glare
“Glare”, like “noise” is a term that is difficult to define, but we know it when we see it.  It refers to unwanted light in the same way that noise is unwanted sound.
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Adaptive Environments
Many spaces are “owned”, either permanently or temporarily, by occupants who want the ability to control their visual environment to optimize the illumination of critical objects, or to avoid glare.
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Light & Vision

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