Interpreting Product Light Specs and Applying to Vray Properly

Cosmos Issues
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  • Hi I am working hard to understand many aspect of Vray for Sketchup and am wondering how I can properly set lighting settings when I have the light specs for a product I am trying to use in a drawing and render to be able to correctly represent the lighting to a client. The product is by Arktura and I am using their “Vapor - Pixel” ceiling tiles. The specs for the product say the colour tempertures available vary from 3000K, 3500K to 4000K. When I use these tempertures in the asset editor the light is dark orange to light orange and does not look anything like 3000K to 4000K light in reality. How does a person convert specs to be able to be applied in vray? I have chosen to use the “rectangle” light and placed it just below the ceiling but between the panels, and am also trying to properly represent what the specs have stated for Lumens which is 1051 per 24" w x 48" L x 3 1/2"H. Rather than using 16 individual rectangle lights under each pannel I tried to multiply the 1051 Lumens output by 16, and used 16816 Luminous Power in the Asset Editor, however the output seems extremely low. Where can I find out how to properly use product lighting specs and convert them (or interpret) them accurately and enter the correct information into the vray asset editor. Finally, I would like to apply these same questions to help understand pendant light fixture settings when I am using actual products that have specifications that are provided. The lighting is extremely important to this project and representing it accurately to the client is extremely important. I really appreciate help with converting light product specs to be accurately represented in Vray for Sketchup, Thank you!

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Hello Laura,

I have responded in the ticket and am also posting here.

V-Ray’s Kelvin to sRGB conversion is generally considered physically accurate.
The conversion formula (sRGB = (Kelvin - 2700) / 95) is designed to approximate human color perception and provide a practical method for mapping Kelvin temperatures to the sRGB color space commonly used in digital imaging. Its accuracy varies very slightly with low Kelvin values (~1000-1800). This formula is based on the standard gamma correction of 2.4 for human visual perception. It helps to map the wider range of colors that can be represented in the Kelvin scale to the more limited range of colors that can be displayed on an sRGB monitor.

While this conversion is widely accepted as a good approximation of how humans perceive color, it’s always a good idea to double-check your results with actual color calibration tools or by comparing them to known color standards. There isn’t a single, universally accepted Kelvin to sRGB table for referencing colors, as color perception can vary among individuals. However, you can find several online resourcesand calculators that provide approximations of the sRGB values for different Kelvin temperatures.

“When I use these tempertures in the asset editor the light is dark orange to light orange and does not look anything like 3000K to 4000K light in reality.”
The discrepancy between the Kelvin values and the perceived colors of light in real life can be attributed to different factors:

  • Light source characteristics: The Kelvin temperature is a measure of the color temperature of a light source, which describes the distribution of energy across the visible light spectrum. However, the actual color of a light source depends on various factors, such as the type of light bulb (incandescent, fluorescent, LED, etc.), the materials used in the light source, and even the age and condition of the light bulb. For example, an incandescent light bulb with a Kelvin temperature of 2700K may appear warmer than a LED light bulb with the same Kelvin temperature due to differences in their spectral composition.
  • Environmental factors: The color of a light source can also be influenced by the surrounding environment. For instance, the color of a light source may appear different when viewed in a room with painted walls, furniture, and other objects, compared to viewing it outdoors or in a different setting.
  • Atmospheric conditions: Factors such as atmospheric scattering, humidity, and air pollution can cause changes in the color of the light, making it difficult to precisely match the Kelvin temperature to the perceived color.
  • Camera and display limitations: When capturing and displaying images, there are inherent limitations in the technology used. Cameras and displays have a finite number of color channels and dynamic range, which can result in a simplified representation of the complex color spectrum in the real world.
  • Personal color perception: Color perception can be highly subjective and varies from person to person.

I am happy to have a look at the model and help achieve “more accurate” lighting while explaining the settings.
If that is alright please share the project with us. Further instructions are provided in the ticket ticket 219254