Comparison of dynamic lighting methods ray tracing vs. path tracing | ENBLE

Comparison of dynamic lighting methods ray tracing vs. path tracing | ENBLE

Ray Tracing vs. Path Tracing: A Battle of Lighting Techniques

Quake 2 looks stunning with path traced lighting

Ray tracing and path tracing have been at the center of a heated debate in the gaming and GPU manufacturing communities for years. On one side, there are those who see ray tracing as the next generation of in-game lighting, delivering previously impossible visual effects. On the other side, critics argue that the cost of supporting hardware and its impact on frame rates make it impractical. However, path tracing offers a promising alternative that is both visually appealing and less demanding on a GPU.

What is Ray Tracing?

Ray tracing is a lighting technique that models light realistically in a scene. Originally developed in the late 1960s, it has only recently become feasible for real-time games due to its computational demands. The process involves casting rays into a scene from the player’s viewpoint, and as each ray interacts with objects, its effects, such as color, transparency, and orientation, are calculated. The ray continues to bounce around the scene until it intersects with a light source. This complex calculation is performed for every pixel, resulting in a highly realistic lighting effect.

While ray tracing has long been used in movie CGI, the launch of Nvidia’s RTX graphics cards and improved computing power has enabled real-time ray tracing in games. Initially limited to shadows and reflections, it has now expanded to include global illumination in some games, transforming the visual experience.

What is Path Tracing?

Path tracing is a modern method of modeling real-time dynamic lighting in a scene. Developed in the mid-1980s, it takes a different approach by sending out multiple rays from a light source and tracking their random bounces in the scene. Unlike ray tracing, which tracks every ray from pixel to source, path tracing only follows a sample of rays based on the most likely path the light would take. This combination of ray tracing and Monte Carlo simulation reduces the computational overhead while providing comparable lighting effects.

Path tracing offers a higher degree of granularity, allowing for greater detail and more realistic lighting. However, it is important to note that path tracing results may require additional denoising algorithms to enhance the image quality. Certain objects, like reflective and refractive surfaces, may require adjustments to avoid loss of information in smaller samples, with some cases resorting to brute force ray tracing for accuracy.

Ray Tracing vs. Path Tracing: Which is Better?

Some ray tracing lighting effects just aren’t worth the cost

Ray tracing is known for its accurate and realistic lighting, following the natural path of light propagation in a scene. However, the computational requirements are enormous, even with hardware acceleration. Games that claim to support ray tracing often utilize it only for specific elements like shadows or reflections.

Path tracing, on the other hand, produces equally impressive visuals while imposing less strain on rendering hardware. It has been successfully implemented in games like Quake II RTX, Portal RTX, and the Overdrive mode update for Cyberpunk 2077. Path tracing has also been modded into older games, such as Half-Life 2, with stunning results.

Overall, path tracing offers a more visually appealing and less demanding solution for dynamic lighting in games. Yet, there are instances where ray tracing is still necessary to ensure visual accuracy, especially when limited path-traced sample sizes might compromise the realism. It’s important to consider the specific requirements of each scene and choose the appropriate technique accordingly.

Looking towards the future, as graphics cards become more powerful, we are likely to see a combination of lighting effects in upcoming games. Both ray tracing and path tracing have their strengths and will continue to coexist until they can be easily rendered with minimal impact on performance.

In the end, it’s the gamers and developers who will benefit from this ongoing battle of lighting techniques, as they unlock new levels of realism and immersion in the virtual worlds they explore.