
Imagine hiking to a lake on a summer day - sitting under a shady tree and watching the water gleam under the sun.
In this scene, the differences between light and shadow are examples of direct and indirect lighting.
The sun shines onto the lake and the trees, making the water look like it's shimmering and the leaves appear bright green. That's direct lighting. And though the trees cast shadows, sunlight still bounces off the ground and other trees, casting light on the shady area around you. That's indirect lighting.
For computer graphics to immerse viewers in photorealistic environments, it's important to accurately simulate the behavior of light to achieve the proper balance of direct and indirect lighting.
What Is Direct and Indirect Lighting? Light shining onto an object is called direct lighting.
It determines the color and quantity of light that reaches a surface from a light source, but ignores all light that may arrive at the surface from any other sources, such as after reflection or refraction. Direct lighting also determines the amount of the light that's absorbed and reflected by the surface itself.
Direct lighting from the sun and sky. Light bouncing off a surface, illuminating other objects is called indirect lighting. It arrives at surfaces from everything except light sources. In other words, indirect lighting determines the color and quantity of all other light that arrives at a surface. Most commonly, indirect light is reflected from one surface onto other surfaces.
Indirect lighting generally tends to be more difficult and expensive to compute than direct lighting. This is because there is a substantially larger number of paths that light can take between the light emitter and the observer.
Direct and indirect lighting in the same setting. What Is Global Illumination? Global illumination is the process of computing the color and quantity of all light both direct and indirect that is on visible surfaces in a scene.
Accurately simulating all types of indirect light is extremely difficult, especially if the scene includes complex materials such as glass, water and shiny metals - or if the scene has scattering in clouds, smoke, fog or other elements known as volumetric media.
As a result, real-time graphics solutions for global illumination are typically limited to computing a subset of the indirect light - commonly for surfaces with diffuse (aka matte) materials.
How Are Direct and Indirect Lighting Computed? Many algorithms can be used for computing direct lighting, all of which have strengths and weaknesses. For example, if the scene has a single light and no shadows, direct illumination is trivial to compute, but it won't look very realistic. On the other hand, when a scene has multiple light sources, processing them all for each surface can become expensive.
To tackle these issues, optimized algorithms and shading techniques were developed, such as deferred or clustered shading. These algorithms reduce the number of surface and light interactions to be computed.
Shadows can be added through a number of techniques, including shadow maps, stencil shadow volumes and ray tracing.
Shadow mapping has two steps. First, the scene is rendered from the light's point of view into a special texture called the shadow map. Then, the shadow map is used to test whether surfaces visible on the screen are also visible from the light's point of view. Shadow maps come with many limitations and artifacts, and quickly become expensive as the number of lights in the scene increases.
Stencil shadows in Doom 3' (2004). Image source: Wikipedia. Stencil shadow volumes are based on extruding scene geometry away from the light, and rendering that extruded geometry into the stencil buffer. The contents of the stencil buffer are then used to determine if a given surface on the screen is in shadow or not. Stencil shadows are always sharp, unnaturally so, but they don't suffer from common shadow map problems.
Until the introduction of NVIDIA RTX technology, ray tracing was too costly to use when computing shadows. Ray tracing is a method of rendering in graphics that simulates the physical behavior of light. Tracing the rays from a surface on the screen to a light allows for the computation of shadows, but this can be challenging if the light comes from one point. And ray-traced shadows can quickly get expensive if there are many lights in the scene.
More efficient sampling methods were developed to reduce the number of rays required to compute soft shadows from multiple lights. One example is an algorithm called ReSTIR, which calculates direct lighting from millions of lights and shadows with ray tracing at interactive frame rates.
Direct illumination and ray-traced shadows created with ReSTIR, compared to a previous algorithm. What Is Path Tracing? For indirect lighting and global illumination, even more methods exist. The most straightforward is called path tracing, where random light paths are simulated for each visible surface. Some of these paths reach lights and contribute to the finished scene, while others do not.
Path tracing is the most accurate method capable of producing results that fully represent lighting in a scene, matching the accuracy of mathematical models for materials and lights. Path tracing can be very expensive to compute, but it's considered the holy grail of real-time graphics.
Comparison of path tracing with a less complete ray-tracing algorithm and rasterization. How Does Direct and Indirect Lighting Affect Graphics? Light map applied to a scene. Image courtesy of Reddit. Direct lighting provides the basic appearance of realism, and indirect lighting makes scenes look richer and more natural.
One way indirect lighting has been used in many video games is through omnipresent ambient light. This type o
Most recent headlines
05/01/2027
Worlds first 802.15.4ab-UWB chip verified by Calterah and Rohde & Schwarz to be ...
04/08/2026
Dalet, a leading technology and service provider for media-rich organizations, t...
04/07/2026
April 7 2026, 19:00 (PDT) Detective Conan: Fallen Angel of the Highway Opens in...
01/06/2026
January 6 2026, 05:30 (PST) Dolby Sets the New Standard for Premium Entertainment at CES 2026
Throughout the week, Dolby brings to life the latest innovatio...
02/05/2026
Dalet, a leading technology and service provider for media-rich organizations, t...
01/05/2026
January 5 2026, 18:30 (PST) NBCUniversal's Peacock to Be First Streamer to ...
17/04/2026
The World Fencing League (WFL) has announced DAZN as its primary global streamin...
17/04/2026
ARRI Releases ALEXA 35 SUP 6.0 and LPS-1 SUP 1.3 Software Updates
ARRI has announced software updates for its ALEXA 35 Live camera and Live Production System L...
17/04/2026
Sennheiser has announced Spectera Studio, an offline system planner for its Spec...
17/04/2026
Deltatre and the German Football Association (DFB) have announced DFB.TV+, a DFB-owned direct-to-consumer streaming service developed and operated by Deltatre. ...
17/04/2026
Global sports marketing agency IMG has announced new senior leadership roles, designed to strengthen how it supports rightsholders and partners in the midst of ...
17/04/2026
NAGRAVISION and Harmonic have announced a watermarking-as-a-service solution for...
17/04/2026
NETGEAR and EVS Broadcast Equipment have announced a global technology partnersh...
17/04/2026
America's broadcasters are launching the NEXTGEN TV Converter Box Program, a new initiative designed to provide millions of American viewers with a low-cost...
17/04/2026
Quantum Corp. will exhibit at NAB Show 2026 (Booth N1726), presenting what it ca...
17/04/2026
Leadership and Staff Announce '20/20 Vision' Playbook...
17/04/2026
TNT Sports has announced a multi-year agreement for U.S. media rights to the FIA World Endurance Championship (WEC). Three events will air on truTV - the 24 Hou...
17/04/2026
Scripps Sports has announced a multi-year broadcast partnership with PBR (Profes...
17/04/2026
Adder Technology, a specialist in connectivity solutions and high performance IP KVM, today announced the latest release of AIM, its IP KVM matrix management so...
17/04/2026
Victory , a free sports streaming platform from A Parent Media Co. Inc. (APMC), has announced a multi-year content distribution partnership with the Dallas Cowb...
17/04/2026
In-venue and creative video staffers at the professional and collegiate level have one major thing in common: the intensity and attention to detail ramps up dur...
17/04/2026
Quickplay has announced the full-scale deployment of Gray Media's streaming ...
17/04/2026
Clear-Com has introduced the FreeSpeak Cell cellular-based wireless intercom system that uses LTE and 5G infrastructure to support large-scale production commun...
17/04/2026
The 2026 NAB Show kicks off Saturday, April 18, with the show floor and exhibits opening April 19-22 at the Las Vegas Convention Center. The show features more ...
17/04/2026
Ratings Roundup is a rundown of recent rating news and is derived from press rel...
17/04/2026
Versatile ribbon mic kit revealed
The latest arrival to the AEA line-up brings together three contrasting models from their Nuvo range, delivering a versati...
17/04/2026
Revealed following sold-out MPG Awards ceremony
Following another sold-out MPG Awards ceremony at The Troxy in London, the MPG have released a full list of ...
17/04/2026
L3Harris towed array systems provide U.S. Navy submarines with extended acoustic...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Cobalt Digital and SineSix Media Partner to Transform Accessibility Compliance into a More Engaging Viewer Experience at NAB Show 2026
Collaboration integrates...
17/04/2026
Strengthening Appear's North America team with a new Vice President of Business Development
Appear ASA (Appear, OSE: APR), a global leader in live producti...
17/04/2026
New framework helps broadcasters, streaming platforms, and sports organizations apply AI to live video for monetization, metadata, highlights, and downstream wo...
17/04/2026
New whitepaper gives broadcasters and OTT operators independent, codec-by-codec evidence that the VisualOn Optimizer transforms viewer quality of experience.
V...
17/04/2026
Blackmagic Design Announces New Blackmagic URSA Cine Immersive 100G
Brie Clayton April 17, 2026
0 Comments
World's first immersive cinema camera f...
17/04/2026
NAB 2026: Vubiquity and Eluvio Showcase Streaming Solution that Significantly Re...
17/04/2026
What Makes a Good Marathon Running Playlist? We asked Xander Dawson, an eighth-semester saxophone major at Boston Conservatory running the Boston Marathon thi...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
At NAB Show 2026, PTZOptics (Booth N1902) will showcase a live sports streaming demo created in collaboration with Moondream, offering a new look at how Visual ...
17/04/2026
The Eindhoven University of Technology is a research university in the Netherlands spanning 25 buildings, specialising in engineering, science and technology. D...
17/04/2026
Documentary Editor - US, Remote
Brie Clayton April 17, 2026
0 Comments
Documentary Editor
April 13, 2026Freelance Video Cameraman - Los......
17/04/2026
Blackmagic Design Announces New Blackmagic URSA Cine 12K LF 100G
Brie Clayton April 17, 2026
0 Comments
Revolutionary digital film camera brings cinem...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
17/04/2026
Dubformer, the AI-powered dubbing platform, and Adapt, a global leader in AI-driven localization and dubbing solutions, have enabled Goalcast, the inspirational...