Path Tracing Quake in Blender

> Texture coordinates can be encoded as Blender UV maps.

Will note that one minor detail about the Quake map format you may find interesting... Quake does not encode the texture coordinates for vertexes in the map. Instead, Quake encodes the coordinate system for textures of each face. This is transformed to screen-space during rendering.

This is different from modern renderers, which record the texture coordinates of vertexes.

Quake's system is less flexible, can't be used for character models, and can be inconvenient during asset creation, but it is a bit faster and more convenient at run-time. When you're rendering, you want to know the gradient of texture coordinates in the X and Y direction on screen, which is easy to calculate using Quake's system.

(Obviously the author knows this, but it wasn't spelled out in the article.)

I'd love to see if the fake water surface texture could be replaced with a procedural deformation faking waves so that the path tracing could render caustics.

I never like projects like this. They always claim that they don't change the mood, theme, or atmosphere but maybe my definition of that is different. They definitely feel like they change the mood and atmosphere to me.

This was actually one of the first things I did with Blender when I got it! When I was a teen and Blender was at 2.5 or 2.6, I booted it up and tried to recreate the lighting in some Quake 2 maps that I had downloaded. Then I used the Shift + ` shortcut to go into first-person and re-explore my childhood in 15-fps ray-traced perfection.

This has nothing to do with biology, it's an argument from signal processing, which is well-understood theory (Nyquist's theorem and so on). If an object oscillates at 1 MHz, and you take 1 million still frames per second, it will rest in the same place in every frame, and thus look static. In reality, such an object would look blurred to the human eye.(+) It's this kind of artifact that motion blur (to be more precise, low-pass filtering) can avoid.

Edit: The article you linked to is very confused about some basic terminology. It equates response time artifacts of an LCD monitor that display sharp, digital images with motion blur. That's so wildly wrong I'm not even sure where to start. Maybe here: When displaying video, motion blur is a property of the source, response time one of the output device.

(+) Edit 2: To expand on this, the human vision system integrates arriving photons over time, and this way implicitly behaves a lot like a low-pass filter. A low-pass filter is different from a fixed-rate shutter, which is what people mean when they say the eye doesn't have a fixed framerate. However, there is a limited temporal resolution.

A more everyday example of this effect would be a dimmed LED. You can pulse an LED at 1 MHz, it will look dimmed, not blinking. But when filming/rendering this LED at 1 million still images per second, it will either be all on or all off, both of which are wrong (i.e., an artifact of your chosen shutter speed).