I am reading this paper [Practical Path Guiding for Efficient Light-Transport Simulation, Müller et al, 2017] and it contains the following sentence:

In practice, however, we recommend combining path-guiding with NEE via multiple importance sampling due to the ease of im- plementation and low performance overhead.

What does NEE stand for? I have found some other authors using this abbreviation, but no explanation.

  • 4
    $\begingroup$ Next event estimation. It is when you sample a point on a light surface and then connect to it from the current vertex. It's also known as a shadow ray. It's basically integration over the surface area of light sources. $\endgroup$
    – lightxbulb
    Dec 1, 2021 at 21:54
  • 2
    $\begingroup$ It's also known as light sampling. $\endgroup$
    – Peter
    Dec 2, 2021 at 18:35

1 Answer 1


"NEE" stands for Next Event Estimation algorithm. For learning more about this algorithm, you can watch this presentation from TU Wien or have a look on their presentation slides.

Also, you can find a useful piece of code for NEE in this presentation.


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