Ray Tracing Explained

Introduction

Ray tracing has been hailed as the future of gaming graphics, promising photorealistic lighting, reflections, and shadows. But what exactly is ray tracing, how does it work, and most importantly—is the performance hit worth the visual upgrade?

In this comprehensive guide, we'll break down the technology behind ray tracing, examine its visual benefits, analyze the performance costs, and help you decide whether you should enable it in your games.

What Is Ray Tracing?

At its core, ray tracing is a rendering technique that simulates the physical behavior of light. Unlike traditional rasterization techniques that have dominated real-time 3D graphics for decades, ray tracing actually traces the path of light rays as they interact with virtual objects—much closer to how light behaves in the real world.

Traditional Rasterization vs. Ray Tracing

To understand why ray tracing is such a big deal, we need to first understand how games have traditionally rendered graphics:

Rasterization has been the standard for real-time 3D graphics because it's fast and efficient. Game developers have created impressive lighting effects using techniques like shadow mapping, screen space reflections, and pre-baked lighting. However, these techniques are ultimately approximations with various limitations.

Ray tracing, on the other hand, calculates how light actually behaves—bouncing off surfaces, being blocked to create shadows, and reflecting or refracting through different materials. This results in much more realistic lighting, but at a significant computational cost.

How Ray Tracing Works

In its simplest form, ray tracing works by tracing the path of light rays from the camera (your viewpoint) into the scene. When a ray intersects with an object, the algorithm calculates how light would interact with that surface based on its material properties.

The ray might:

• Reflect off a shiny surface
• Refract through transparent materials like glass or water
• Be blocked by an opaque object, creating shadows
• Scatter in various directions (diffuse reflection)
• Be partially absorbed, giving objects their color

In full path tracing (the most comprehensive form of ray tracing), rays can bounce multiple times throughout the scene, capturing complex light interactions like color bleeding and indirect illumination. However, this is extremely computationally expensive, which is why games use optimized versions with limited ray bounces and hybrid approaches that combine ray tracing with traditional techniques.

Ray Tracing Effects in Games

Current games typically implement ray tracing for specific effects rather than using it for all lighting calculations. Here are the most common ray-traced effects you'll find in modern games:

1. Ray-Traced Reflections

Perhaps the most noticeable ray tracing effect, RT reflections allow for accurate reflections on any surface—not just flat mirrors or water. This means curved surfaces, rough metals, and even partially reflective materials can all show proper reflections of the surrounding environment, including off-screen elements that traditional screen space reflections can't capture.

Games that showcase this well: Cyberpunk 2077, Marvel's Spider-Man Remastered, Control

2. Ray-Traced Shadows

Ray-traced shadows are more accurate and realistic than traditional shadow mapping techniques. They can properly represent soft shadows with accurate penumbra (the partially shadowed area), contact hardening (shadows that get softer the further they are from the object casting them), and can account for complex light interactions through semi-transparent objects.

Games that showcase this well: Shadow of the Tomb Raider, Dying Light 2, Metro Exodus Enhanced Edition

3. Ray-Traced Global Illumination

This is perhaps the most transformative ray tracing effect, as it simulates how light bounces off surfaces and illuminates other areas indirectly. Traditional games often use pre-baked lighting or approximations that can't react to dynamic elements. Ray-traced global illumination creates realistic ambient lighting that changes in real-time as objects and light sources move.

Games that showcase this well: Metro Exodus Enhanced Edition, Cyberpunk 2077, Portal RTX

4. Ray-Traced Ambient Occlusion

Ambient occlusion darkens areas where objects are close together or in corners, simulating how less light reaches these areas. Ray-traced ambient occlusion is more accurate than screen space techniques, especially for complex geometry, and works correctly with off-screen objects.

Games that showcase this well: Control, Battlefield V, Resident Evil Village

5. Ray-Traced Caustics

Caustics are the patterns of light created when light rays are reflected or refracted by curved surfaces, like the rippling patterns at the bottom of a swimming pool. These are extremely difficult to simulate with traditional techniques but can be rendered naturally with ray tracing.

Games that showcase this well: Atomic Heart, Hitman 3, Minecraft RTX

The Visual Impact of Ray Tracing

The visual improvement from ray tracing varies significantly depending on the game, the specific effects implemented, and the environment you're in. Here's a breakdown of when ray tracing makes the biggest difference:

Where Ray Tracing Shines

• Urban environments with lots of glass and reflective surfaces: Cities in games like Cyberpunk 2077 are transformed by ray-traced reflections, with every window and puddle accurately reflecting the neon signs and buildings around them.
• Indoor scenes with complex lighting: Games like Control showcase how ray-traced global illumination can create much more realistic indoor lighting, with light properly bouncing off walls and illuminating dark corners.
• Water and transparent surfaces: Ray tracing excels at rendering realistic water with proper reflections, refractions, and caustics.
• Night scenes with multiple light sources: Ray tracing accurately captures how multiple colored lights interact with the environment and each other.

Where Ray Tracing Is Less Noticeable

• Fast-paced gameplay: In competitive shooters or racing games, you might be moving too quickly to appreciate the subtle lighting improvements.
• Outdoor daylight scenes: Traditional lighting techniques are often quite good at simulating simple direct sunlight, making ray tracing less transformative in these environments.
• Stylized or non-photorealistic games: Games with cartoon-like or stylized art directions might not benefit as much from physically accurate lighting.
• Games with excellent pre-baked lighting: Some games have invested heavily in high-quality pre-baked lighting that can look nearly as good as ray tracing in static environments.

The Performance Cost

Now for the big question: what kind of performance hit should you expect when enabling ray tracing?

Typical Performance Impact

Based on our extensive testing across multiple games and hardware configurations, here's what you can generally expect:

These numbers can vary significantly based on:

• Your GPU: RTX 40-series cards handle ray tracing much more efficiently than RTX 20-series or AMD RX 7000 series
• Resolution: The performance hit is generally larger at higher resolutions
• Game optimization: Some games implement ray tracing more efficiently than others
• Scene complexity: Complex scenes with many reflective surfaces or light sources will see a bigger hit

Real-World Examples

Here are some specific examples from our benchmarks (tested on an RTX 4070 at 1440p):

As you can see, the performance hit is substantial—often cutting framerates nearly in half in the most demanding implementations.

The Upscaling Solution: DLSS, FSR, and XeSS

The significant performance hit from ray tracing is why upscaling technologies have become so important in modern gaming. These technologies render the game at a lower resolution and then use various techniques to upscale the image to your target resolution, recovering much of the performance lost to ray tracing.

NVIDIA DLSS (Deep Learning Super Sampling)

DLSS uses AI and dedicated Tensor cores on RTX graphics cards to upscale images with impressive quality. The latest version, DLSS 3.5, includes:

• DLSS Super Resolution: AI-based upscaling from a lower resolution
• DLSS Frame Generation: AI generates entirely new frames between rendered ones (RTX 40-series only)
• DLSS Ray Reconstruction: Improves the quality of ray-traced effects specifically

DLSS can recover 40-100% of the performance lost to ray tracing, depending on the quality mode used and whether Frame Generation is available.

AMD FSR (FidelityFX Super Resolution)

FSR is AMD's upscaling solution that works on a wider range of hardware (including NVIDIA GPUs). The latest version, FSR 3.0, includes:

• FSR Super Resolution: Spatial upscaling algorithm (no AI)
• FSR Frame Generation: Similar to DLSS Frame Generation but using different techniques

FSR typically recovers 30-80% of lost performance, with slightly lower image quality than DLSS in most comparisons.

Intel XeSS

Intel's XeSS is similar to DLSS but designed to work on a wider range of hardware. It uses AI-assisted upscaling and can recover 30-70% of performance, with quality somewhere between DLSS and FSR in most implementations.

Performance with Upscaling

Here's how our previous benchmarks look with upscaling enabled (DLSS/FSR Quality mode):

With upscaling, ray tracing becomes much more viable, often bringing performance back to near-native levels while maintaining most of the visual benefits.

Is Ray Tracing Worth It?

Now for the million-dollar question: should you enable ray tracing in your games? The answer depends on several factors:

When Ray Tracing Is Worth It

• You have a high-end GPU: RTX 30/40-series or RX 7900 series
• You value visual quality over raw performance: You're willing to accept 60 FPS instead of 100+ FPS for better visuals
• You're playing slower-paced, visually rich games: Single-player adventures, atmospheric horror games, etc.
• The game has excellent ray tracing implementation: Control, Cyberpunk 2077, Metro Exodus Enhanced Edition
• You're using DLSS/FSR: Upscaling technologies make ray tracing much more viable

When Ray Tracing Isn't Worth It

• You have a mid-range or older GPU: The performance hit may be too severe
• You're playing competitive games: Higher framerates are usually more important than visual fidelity
• The game has poor ray tracing implementation: Some games add ray tracing as an afterthought with minimal visual improvement
• You're gaming on a laptop: Ray tracing is particularly demanding on mobile GPUs and can drain battery quickly
• You're already struggling to maintain good framerates: If you're barely hitting 60 FPS with ray tracing off, enabling it will likely result in a choppy experience

Our Recommendations by GPU Tier

The Future of Ray Tracing

Ray tracing is still in its early stages for real-time gaming. As hardware and software continue to evolve, we can expect:

• More efficient implementations: Developers are still learning how to optimize ray tracing
• Better hardware acceleration: Future GPUs will handle ray tracing with less performance impact
• More comprehensive ray tracing: Moving beyond selective effects to fully ray-traced rendering
• Better upscaling technologies: DLSS and FSR will continue to improve, further mitigating the performance hit
• Path tracing: More advanced than current ray tracing, with multiple light bounces for even more realistic lighting (already seen in Minecraft RTX and Portal RTX)

The upcoming console refresh (PS5 Pro and next-gen Xbox) will likely place a greater emphasis on ray tracing, which should accelerate adoption and optimization in cross-platform titles.

Conclusion

Ray tracing represents a significant leap forward in real-time graphics technology, offering more realistic lighting, reflections, and shadows than ever before. However, the substantial performance cost means it's not always the right choice for every gamer or every game.

If you have a recent high-end GPU and value visual fidelity in slower-paced games, ray tracing combined with DLSS/FSR can provide a truly next-generation visual experience. For competitive gamers or those with older hardware, the traditional rasterization approach still offers the best balance of performance and visuals.

As with most graphics settings, we recommend experimenting with different ray tracing options in your favorite games. You might find that enabling just ray-traced reflections gives you most of the visual benefit with a more manageable performance hit, or that some games look dramatically better with ray tracing than others.

Ultimately, whether ray tracing is "worth it" is a personal decision based on your hardware, the games you play, and how you balance visual quality against performance. But one thing is certain: ray tracing is here to stay, and it will only become more prevalent and efficient in the coming years.