What is the new "New light solver" in Corona Renderer 1.7?



What is it?


The New light solver (experimental) option found under Render Setup > Performance toggles new experimental method of rendering lights introduced in Corona Renderer 1.7. 

This optional new algorithm can speed up your renders by up to 6 times by learning which scene lights are important at a particular location. Those lights then receive more rays than the others, resulting in a lower noise level.


Enabling this option may significantly reduce render times in scenes:

  • With many lights (e.g. 10 or more)
  • Where lights have complex shapes
  • With complex lighting scenarios (e.g. if the lights are occluded by some objects, blocking the path from the light source to the camera)




Why is it off by default?


The new light solver is still a work in progress. Generally it should work well, but disabling it by default was a safety measure we decided to include in the 1.7 release. 




How to use it?


Currently (Corona Renderer 1.7) the preferred workflow is:

  1. Enable the New light solver option
  2. Render your image to reasonable quality (when no excessive noise is visible)
  3. If no issues are visible in the rendered image - there is nothing to worry about, and the option can be left enabled
  4. If some issues are visible, such as rectangle-shaped dark artifacts, excessive noise in specific areas of the image, incorrect light appearance, dark highlights on reflective surfaces - then disable the option, and re-render




Future improvements


We are planning to improve this new light rendering technology in the upcoming version 2 of Corona Renderer, so that it would be enabled by default, and could be safely used in all scenarios. 




Examples


New light solver option disabled:



New light solver option enabled: