Question

How does radiosity for a surface differ from the emitted energy? For what kinds of surfaces are these two quantities identical?

Short answer

Answer: The main difference between radiosity and emitted energy is that radiosity includes both the self-emitted energy of a surface and the reflected energy from other surfaces, while emitted energy only includes the energy generated by the surface itself. These two quantities are identical for perfect black bodies or perfect emitters, where there is no reflected energy from other sources.

Step-by-step solution

Define Radiosity

Radiosity is the total amount of radiant energy leaving a surface per unit area. It is the sum of the self-emitted energy and the reflected energy from other surfaces in the environment.

Define Emitted Energy

Emitted energy is the energy that is generated and emitted by a surface due to its own emission. This is usually caused by the high temperature of the surface and is not dependent on other surfaces in the environment.

Difference between Radiosity and Emitted Energy

The main difference between radiosity and emitted energy is that radiosity includes both the self-emitted energy of a surface and the reflected energy from other surfaces, while emitted energy only includes the energy generated by the surface itself.

Identical Radiosity and Emitted Energy

The radiosity and emitted energy are identical for surfaces that are perfect black bodies or perfect emitters. These surfaces do not reflect any energy from other sources, and radiosity is equal to the emitted energy solely because all the reflected energy is zero.

Conclusion

In summary, radiosity and emitted energy differ in that radiosity accounts for both self-emitted energy and reflected energy from other surfaces, while emitted energy only accounts for the self-generated energy of a surface. These two quantities are identical for perfect black bodies or perfect emitters, where there is no reflected energy from other sources.