Information Technology Reference
In-Depth Information
1. Introduction
1.1 Motivation
1.1.1 Importance of Visual Perception
Visual perception is important for both humans and computers. Humans are visual
animals. Just imagine how loosing your sight would effect you to appreciate its
importance. We extract most information about the world around us by seeing.
This is possible because photons sensed by the eyes carry information about
the world. On their way from light sources to the photoreceptors they interact with
objects and get altered by this process. For instance, the wavelength of a photon
may reveal information about the color of a surface it was reflected from. Sudden
changes in the intensity of light along a line may indicate the edge of an object. By
analyzing intensity gradients, the curvature of a surface may be recovered. Texture
or the type of reflection can be used to further characterize surfaces. The change of
visual stimuli over time is an important source of information as well. Motion may
indicate the change of an object's pose or reflect ego-motion. Synchronous motion
is a strong hint for segmentation, the grouping of visual stimuli to objects because
parts of the same object tend to move together.
Vision allows us to sense over long distance since light travels through the air
without significant loss. It is non-destructive and, if no additional lighting is used, it
is also passive. This allows for perception without being noticed.
Since we have a powerful visual system, we designed our environment to pro-
vide visual cues. Examples include marked lanes on the roads and traffic lights. Our
interaction with computers is based on visual information as well. Large screens
display the data we manipulate and printers produce documents for later visual per-
ception.
Powerful computer graphic systems have been developed to feed our visual sys-
tem. Today's computers include special-purpose processors for rendering images.
They produce almost realistic perceptions of simulated environments.
On the other hand, the communication channel from the users to computers has a
very low bandwidth. It consists mainly of the keyboard and a pointing device. More
natural interaction with computers requires advanced interfaces, including computer
vision components. Recognizing the user and perceiving his or her actions are key
prerequisites for more intelligent user interfaces.
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