Page "Ray tracing (graphics)" Paragraph 17

Although it does handle interreflection and optical effects such as refraction accurately, traditional ray tracing is also not necessarily photorealistic.

True photorealism occurs when the rendering equation is closely approximated or fully implemented.

Implementing the rendering equation gives true photorealism, as the equation describes every physical effect of light flow.

However, this is usually infeasible given the computing resources required.

The realism of all rendering methods, then, must be evaluated as an approximation to the equation, and in the case of ray tracing, it is not necessarily the most realistic.

Other methods, including photon mapping, are based upon ray tracing for certain parts of the algorithm, yet give far better results.