A shadow ray is a ray cast from a visible point on an object towards a light source to determine if that point is in shadow. According to the provided reference, if the shadow ray intersects another object before reaching the light source, the original point is in shadow.
In more detail:
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Purpose: Shadow rays are used in ray tracing to determine if a point on a surface is illuminated by a light source or if it's blocked by another object, thus being in shadow.
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Process:
- A ray is cast from the point visible through a pixel of the frame (the intersection point).
- The ray travels from the intersection point to the light source.
- If the ray intersects any other object along its path to the light source, the original point is considered to be in shadow.
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Impact: Shadow rays directly affect the realism of a rendered image by accurately simulating shadows. Without shadow rays, objects would appear to be uniformly lit, lacking depth and definition.
