whitted

The gist is that in Whitted for each surface hit a single shadow ray per light, a reflection ray and a refraction ray are traced.

Whether software uses that for Whitted ray tracing or path tracing or something else is up to the application.

So classic Whitted ray tracing is mad fast on GPUs, but add global illumination or similar and you've got a problem.

The simplified history is usually presented as Whitted Raytracing -> Distributed Raytracing -> Path Tracing.

POV-ray supports all kind of ray tracing and path tracing techniques, not just Whitted RT.

This is called Whitted ray tracing and is probably what you're referring to.

So, basic Whitted style ray tracer is, for each pixel, project a ray into the scene and see what the closest intersection is.

Back in the day everyone used Whitted style ray tracers to render shiny metal blobs because secular reflections are trivially handled with ray tracing.

Plain Whitted ray tracing handles some additional optical effects that polygon rasterizers aren't good at (reflection, refraction, shadows), but it's not a complete solution.

If you're talking about games, it probably means either path tracing or taking a conventional rasterization engine and bolting Whitted ray tracing on the side because they want realistic reflection and/or shadows.

Does anybody have a reliable link to the Whitted quote?

I believe the article refers specifically to Whitted ray tracing when referring to 'ray-tracing' as opposed to distribution ray tracing or path tracing.

This is implicitly about Whitted Raytracing, which was synonymous with cost effective "raytracing" for a time.

We have now arrived at what we call "Whitted-style ray tracing".

I think the term “distribution ray tracing” was a bit of a mid-point on the timeline of evolution from Whitted ray tracing to today’s path tracing?

You're probably right, but nobody I know calls it "Whitted ray tracing" unless Turner is there in the room, or some point is being made about or in reference to his paper specifically.

Another comparison that is equally astonishing to the RPi is that modern GPUs have exceeded Whitted’s prediction.

Ray tracing - at least Whitted-style ray tracing - is about as simple as physically-based rendering gets.

In traditional Whitted-style ray tracing, the expensive part is indeed figuring out where there is no light.