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Reference: Artificial Lighting values

Here are some values that you can work with in Lumion (2023.0 and newer).  This applies to both the Ray Tracing and also the Rasterization rendering pipeline which work with a (new) unified lighting system.

Lumion now uses real-world measurements for lighting.

See also:

This section from the above article is very useful:

You will also notice that lights are much less visible during the day.  This is because artificial lighting, just as in real life, cannot compete with the Sun's Brightness.

  • The noonday Sun in Lumion measures around 1,600,000,000 Nits and the night sky around 0.001 Nits.
  • Emissiveness has a maximum of 10,000 Nits and Area Lights a maximum of 100,000 Nits (the average for a TV is 500-1500 Nits).
  • Spotlights and Omnilights have a max of 100,000 Lumens. (1.0 Lumen = 0.29 Nits)

So even at maximum settings, artificial lights are far from the Sun's maximum Brightness. This means that you might find you need to lower the Sun/Sky/Real Sky Brightness setting to make artificial lighting more visible during the day (this is for both interiors and exteriors). In other words, the darker the Scene, the more visible artificial light will be.

If you want to have the light cast from an artificial light seen more strongly then the Brightness should be increased.  In some cases that could be up to the maximum Lumens, depending on the balance of direct lighting in the Scene.

See also section: Tips for working with Lights:

 

 

1. Nits:

Used in Lumion for:

  • Area/Line Lights.
  • The Emissive value for a Standard Material (and Billboard Material - based on a Standard Material).
  1. Nits or NITS are a measure of luminance, meaning it is a measure how much light an object emits. Its brightness. (1)

  2. One Nit is equal to one candela (one candlepower) per square meter (1cd/m2). The sun at noon is rated at 1.6 billion nits. (1)

  3. 1 Nit = 3.426 Lumens. To convert Nits to Lumens multiply the number of Nits by 3.426.

 

2. Lumens:

Used in Lumion for:

  • Spotlights.
  • Light from the Sun and ambient light from the sky.

Lumens or ANSI Lumens are used as a measurement of how much light is being projected.

  • 1 Lumen = 0.29 Nits. 1 Nit = 3.426 Lumens.

 

3. Lumens or Nits:

Both are to quantify optical output.

Lumens are a unit of light created/projected.

Nits are a unit of measurement for how much visible light is being seen. Its brightness.

Area and Line Lights use Nits.  If you need to convert or relate Lumens needed for them then see below, section 5.1:  Setting Line Lights to an Equivalent Lumens. 

 

4. Objects:

4.1:  LED Lights 

See this very useful ArchDaily guide:

(credit:  David Hakimi, July 02, 2018, source: ArchDaily)

In general terms:

"For the average space of 250 square feet (edit: 23.23 square meters), you’ll need roughly 5,000 lumens as your primary light source (20 lumens x 250 square feet). In your dining room, you’ll want about 30 lumens per square foot on your dining table (you want to see your food, but not examine it), so if your table is 6 x 3 feet, that’s 540 lumens."

Square feet to square meters: multiple by 0.092903.  Or: Square Feet / 10.764.

20 Lumens per square foot = 215 Lumens per square meter.

Allow also for light absorption in the room, for example, if the walls are dark colored, and also personal preferences for brightness.  For your visualization you may sometimes also choose to over-emphasize the artificial lighting.

 

4.2:  LED signage

Outdoor LED signs can range from 5,000 to 8,000 nits or higher.

Indoor LED signs from 1,000 to 2,000 Nits.

 

4.3:  HDR TVs

"Better-performing HDR TVs typically generate at least 600 Nits of peak brightness, with top performers hitting 1,000 Nits or more.
But many HDR TVs produce only 100 to 300 Nits....
In comparison, typical televisions range from 500 to 1,000 Nits."

4.4:  Lumens for a space

See this site for a guide and for a general calculator of Lumens a room may need:
"1000-3000 lumens per 100 Square Feet
If you're lighting up a new space or don't have a reference point to compare with incandescent or fluorescent lamps, you can also estimate your lighting needs by square footage. For every 100 square feet, 1000 lumens is sufficient for low-light level areas such as living rooms and lounge areas, while task-oriented spaces may require up to 3000 lumens or more."

4.5: Watts

Need to work with Watts and get some general guides on LEDs such as LED Light Bulb A19 and LED Recessed Ceiling Light, etc:

 

5.  FAQ:

5.1:  Setting Line Lights to an Equivalent Lumens

Question:

You are using a Line Light in a Scene and trying to determine the required light output, in Nits so that each has the same Lumens per foot output.

Is the Nits value applied as a per foot value or is it the cumulative output from the entire light?

For example: you have Line Light that is an inch in one dimension and 2 feet in the other.  Do you assign it 31.5 Nits in order to achieve a 31.5 Lumens/foot output? Or assign it 63 nits?

 

Answer:

Nits and Lumens:
Nits (candela/m²,  cd/m²) measures the brightness of a surface.  If you increase the surface area, the light output automatically increases.

Lumens measures the total amount of light emitted. If you spread the same amount of light over a larger area, the perceived brightness decreases.

Conversion:
To achieve 31.5 Lumens per foot, we need to convert Nits to Lumens using the area of the light.

The formula to convert Nits to Lumens is: Lumens=Nits×area×π

Calculating for Your Line Light value:
Your Line Light dimensions: 1 inch width (0.0254 meters) and 2 feet long (0.6096 meters).

Area in square meters: 0.0254×0.6096=0.01551 m²

Desired Lumens: 31.5 Lumens per foot. For a 2-foot light: 31.5×2=63 Lumens.

Using the formula:


You can conclude that to achieve a light output of 31.5 Lumens per foot for your Line Light, you need to set it to approximately 1,300 Nits.

Keep in mind that Nits describe the brightness of the surface.  So increasing the size of the light will proportionally increase the total light output.

 

See Also: