If you are a 3D designer, you may have come across the term HDRi. You might be wondering: what does this term mean? Is it an image extension? A type of photographic technique? Or something else entirely?
In the context of 3D design, HDRi stands for High Dynamic Range Image.
The Meaning of High Dynamic Range
The high dynamic range part of the term HDRi refers to the fact that every pixel in a true HDRi image contains more levels of lighting data than are visible on your screen.
Premium HDRi images like the ones we have here at CGI.Backgrounds contain far more lighting data than the 255 levels in a typical image.
In order to be displayed on a computer screen, HDRi images need to be tone-mapped. That means that the extensive lighting data in each pixel is mapped to the reduced levels of a standard photograph, resulting in an image with a balanced exposure that a traditional monitor can display.
When used in 3D rendering software, however, the extra lighting data in each pixel allows for things like Image-Based Lighting (IBL). With this technique, 3D designers can automatically light a scene using the lighting data stored in the high dynamic range pixels of an HDRi image.
Other Terms for HDRi Images
The abbreviation HDRi is often combined with another word. You might see terms like HDRi Map, HDRi Environment, or HDRi Sky.
HDRi Map is the blanket term for this type of imagery. HDRi Map typically refers to 360° images, often of real-world places, with high dynamic range lighting data.
HDRi Environments are generally HDRi maps of immersive spaces, such as the interior of a race track, the courtyard of a building, or a dramatically lit warehouse interior.
The term HDRi Sky or HDRi Dome usually refers to an HDRi Map of an outdoor location with a wide open sky. HDRi Skies can be a great tool for designers who want to use HDRi imagery to add realistic time-of-day or weather-based lighting to their 3D rendering projects, such as when visualizing a building.
More Resources
If you want to learn more about HDRi images, we have a variety of resources available.
1. Sign up for our free newsletter to get weekly information and updates about HDRi Maps and other 3D rendering tech.
2. Our article about commercial HDRi maps and other images gives you the info you need to select an HDRi map for a commercial project and to avoid common pitfalls.
3. If you need to download HDRi Maps or other HDRi images for your own projects head over to our plans and pricing page to access our premium HDRi images.
