Part 7/10:
A critical feature of path tracing is determining global illumination, which combines both direct and indirect light interactions to achieve a realistic effect. Utilizing shadow rays, calculations ascertain if incoming light from the sources is blocked by any objects. The complexity heightens with the introduction of secondary rays that bounce off surfaces, effectively allowing light to illuminate objects indirectly.
Every interaction contributes to the final image's quality, resulting in gradients, reflections, shadows, and the interplay of colors from nearby objects, enriching the depth of the scene.