Setting up Lighting - Dechetmew/Aquaray-Raytracing-Renderer-for-Unreal-5.2.1 GitHub Wiki

There are currently only four types of Lights Supported: World, Ambient, Sphere and Cone Lights. For Point Lights, Distance Falloff is calculated by Radius for Performance Reasons.

World Light

The World Light color and Direction is set in The Controller actor using the Following Settings:

  • Primary Light Color (1.0 = 100 kilolux)
  • Primary Light Exponent (Multiplies Light Color by this Value)
  • Primary Light Direction
  • Primary Light Height

Ambient Light

Amount of Light in Shadowed Areas is set inside The Controller Actor

  • Ambient Light Color (values should be around 0.15)

Sphere Lights

These Light are Traced in a Full sphere, use only when you need 360 Degree Lighting. The following values are usable:

  • Light Color
  • Attenuation Radius (You can also set Intensity but its not recommended)

Cone Lights

These lights are Traced in a Cone, with the Cone Being Reversible up to almost 180 degrees. This allows controling the exclusion area where Rays arent traced, saving on Performance. The following values are usable:

  • Light Color
  • Attenuation Radius
  • Outer Cone Angle (0 = degrees, 61.5 = about 90 degrees, 80 = almost 180 degrees) (You can also set Intensity but its not recommended)

Figuring out the Color Value

To get the Light Color correct, you must measure how much the surrounding surfaces lit by the Light in Kilolux:

  • Inside the Controller actor, set the Exposure Multiplier to one (Default).
  • Screenshot and paste an Image of the Scene into your Image Editing Software of Choice (Like Paint.net or something like that)
  • Measure the RGB values of a lit surface. An RGB value of 255,255,255 corresponds to 100,100,100 kilolux.
  • Increase or Decrease the Light Color amount until the resulting Environment color is Matching your reference PS: It is recommended to tune Lighting with a White Surface

My (probably inaccurate) method of converting RGB to Average Kilolux is: x = ((r / 255) + (g / 255) + (b / 255) / 3) * 100 Refer to the Chart Below:

ON GROUND VALUES (AVERAGE) Clear sun = 1.000f - 100.0 kilolux Slight haze = 0.800f - 80.0 kilolux Light Clouds = 0.350f - 35.0 kilolux Skylight = 0.175f - 17.0 kilolux Overcast = 0.100f - 10.0 kilolux Heavy overcast = 0.055f - 5.5 kilolux Office Light = 0.040f - 0.4 kilolux Moonlight = 0.0000025f 0.00025 kilolux