I'm learning Ray Tracing using this MIT tutorial:

https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-837-computer-graphics-fall-2012/assignments/MIT6_837F12_assn4.pdf

I've heard Ray Tracing only in the context of lighting. I.e. I understand that ray casting is used to light an object that has been already drawn. However, I've also seen ray casting in the context of just drawing the picture (not lighting). So which one are rays about?

What's the concept of "ray" really?

E.g. in that tutorial one draws the picture like:

image.SetPixel( x, y, pixelColor );

where pixelColor has been acquired from the Ray Caster. But I read this to mean that pixelColor already has lighting information.

I'm learning Ray Tracing using this MIT tutorial.

I've heard Ray Tracing only in the context of lighting. I.e. I understand that ray casting is used to light an object that has been already drawn. However, I've also seen ray casting in the context of just drawing the picture (not lighting). So which one are rays about?

What's the concept of "ray" really?

E.g. in that tutorial one draws the picture like:

image.SetPixel( x, y, pixelColor );

where pixelColor has been acquired from the Ray Caster. But I read this to mean that pixelColor already has lighting information.

I'm learning Ray Tracing using this MIT tutorial:

https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-837-computer-graphics-fall-2012/assignments/MIT6_837F12_assn4.pdf

I've heard Ray Tracing only in the context of lightning. I.e. I understand that ray casting is used to light an object that has been already drawn. However, I've also seen ray casting in the context of just drawing the picture (not lightning). So which one are rays about?

What's the concept of "ray" really?

E.g. in that tutorial one draws the picture like:

image.SetPixel( x, y, pixelColor );

where pixelColor has been acquired from the Ray Caster. But I read this to mean that pixelColor already has lightning information.

I'm learning Ray Tracing using this MIT tutorial:

https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-837-computer-graphics-fall-2012/assignments/MIT6_837F12_assn4.pdf

I've heard Ray Tracing only in the context of lighting. I.e. I understand that ray casting is used to light an object that has been already drawn. However, I've also seen ray casting in the context of just drawing the picture (not lighting). So which one are rays about?

What's the concept of "ray" really?

E.g. in that tutorial one draws the picture like:

image.SetPixel( x, y, pixelColor );

where pixelColor has been acquired from the Ray Caster. But I read this to mean that pixelColor already has lighting information.