4.c) With a neat diagram, explain scalar and multimedia sensing techniques.
Answer:
Scalar sensing
- Scalar sensing encompasses the sensing of features that can be quantified simply by measuring changes in the amplitude of the measured values with respect to time.
- Quantities such as ambient temperature, current, atmospheric pressure, rainfall, light, humidity, flux, and others are considered as scalar values as they normally do not have a directional or spatial property assigned with them. Simply measuring the changes in their values with passing time provides enough information about these quantities.
- The sensors used for measuring these scalar quantities are referred to as scalar sensors, and the act is known as scalar sensing.
A simple scalar temperature sensing of a fire detection event is shown in Figure (a).
Multimedia sensing
- Multimedia sensing encompasses the sensing of features that have a spatial variance property associated with the property of temporal variance.
- Unlike scalar sensors, multimedia sensors are used for capturing the changes in amplitude of a quantifiable property concerning space (spatial) as well as time (temporal).
- Quantities such as images, direction, flow, speed, acceleration, sound, force, mass, energy, and momentum have both directions as well as a magnitude. Additionally, these quantities follow the vector law of addition and hence are designated as vector quantities. They might have different values in different directions for the same working condition at the same time.
- The sensors used for measuring these quantities are known as vector sensors.
A simple camera-based multimedia sensing using surveillance as an example is shown in Figure (b).
