If you've used a ray/path tracer you know that the output always starts out noisy - rays are very discrete things so you need to trace a lot of them if you want things like soft shadows, global illumination, depth of field and motion blur. The noise comes from the fact that scattered rays are sent towards different directions for each pixel.
But there's nothing stopping you from just, not doing that
glossary
exegfx — Abbreviation of executable graphics.executable graphics — Demoscene artwork format, in which a small executable renders a single still image. Typically, the executable is constrained to 4 kilobytes in size, with rendering time limited to 30 seconds.
demoscene — Computer art subculture focused on producing audiovisual art in the form of software.
With the piece above (Danmarksfärjan), it was extremely important to me that the smooth plastic surfaces should appear smooth in the final render, rather than having visible noise. To that end, I used the exact same unscrambling technique above (albeit implemented by hand in my rendering framework rather than in Blender), trading off high-frequency noise for lower-frequency artifacts that are visible in the shadows/reflections if you zoom in close.
