Path tracing will arrive in Cyberpunk 2077 on April 11, how is it different from ray tracing?

CD Projekt RED has confirmed during this year’s GDC that Cyberpunk 2077 will receive patch 1.62 on April 11, and that this update will add the RT Overdrive modea setting that will greatly improve the graphic quality of the game thanks to the use of the path tracing. With this patch, Cyberpunk 2077 will become the fourth game available on PC, along with Minecraft, Portal, and Quake II RTX, that uses this rendering method.

I think before we get into the changes that RT Overdrive mode will offer, it is important to analyze the differences between path tracing and ray tracingtwo technologies that for many are practically analogous, but that deep down present differences of such important nuances that make them deserve to be considered and valued in a different way.

We can say that, in general, these two technologies aim to more realistically recreate the interactions of light rays in each scene. Both can produce graphics with a level of quality higher than what we would obtain with the classic rasterization process, which uses classic texture maps for lighting and shading, and screen space reflections. However, as we anticipate, they also have important differences that we are going to explain below.

Ray tracing vs path tracing

path tracing 2

Ray tracing projects rays in all directions from different locations, follows the path of light and its interactions with different targets by calculating misses and collisions, and possible ricochets resulting from such collisions. This allows you generate more realistic images with less noise, but it also implies high cost at the performance level.

When we talk about path tracing, we can say that broadly speaking it is a simple evolution of ray tracing, because both technologies have the same objective and only differ in the way in which they work to achieve it. This technique can fire large numbers of rays per pixel simultaneously that behave randomly, which greatly improves image quality.

Despite this greater number of rays, path tracing can work with complex scenes in which a large number of objects concur. in a very efficient waysince it uses integral equations throughout the process that help to solve complicated situations using the obtained samples in an optimal way.

These equations make it is not necessary to use all the rays to generate the pixels in the final scene. It also does not calculate as large a number of bounces as in ray tracing, since it is possible to set limits on the total number of bounces, and these end when a light source is reached or when the set limit is reached.

path tracing ray tracing raster

On the other hand, this technology also choose those ray paths that are considered “ideal” taking into account key aspects such as camera position, light sources and bounce. Starting from everything we have said, the number of samples per pixel is adjusted, and in this way it is possible to refine the quality of the image.

This means that it is part of a very complex process where we can find thousands of rays at first, but that thanks to the algorithms and integral equations it is being simplified to achieve a realistic result in a more efficient wayreducing both the number of samples used and the amount of bounces.

In the end, this has a very positive impact on image quality, since the first interactions and bounces of light are the most noticeable when it comes to giving color to the scene. However, it is also important to note that in scenes where we have a lot of reflections and refractions ray bounces are more important, and in these cases ray tracing achieves better results, although you can also adjust the path tracing algorithm to increase the amount of bounces used in the samples to compensate.

in both techniques a final noise reduction process needs to be applied to the image, since the result that we obtain after using ray tracing or path tracing is an image that can look quite “dirty”, as you can see in the attached video. The noise in the image will largely depend on the number of rays (total samples) that have been used to generate it. Obviously, the greater the number of rays and bounces, the higher the image quality, but also the greater the impact on performance.

GeForce RTX 20 and higher graphics cards speed up ray tracing and path tracing through RT coresand use the tensor cores for final noise reduction process. For their part, the Radeon RX 6000 and RX 7000 use ray tracing accelerators for the key tasks associated with both technologies.

How Cyberpunk 2077 will improve with path tracing

Now that you are clear about the differences between ray tracing and path tracing, it is a good time to start to see the improvements that patch 1.67 will introduce in Cyberpunk 2077. As we have said, this patch will bring a new graphic mode called RT Overdrive, which will apply layout of roads for improve lighting, shadows and reflections. This is the official description offered by NVIDIA and CD Projekt RED:

  • More realistic lighting with NVIDIA RTX Direct Illumination (RTXDI)which will make each light source in the game generate accurate and realistic light, capable of directly and indirectly affecting all elements in the game, also generating more realistic shadows and scenes with accurate color.
  • Both lighting and reflections will now have multiple bounces (until now only one bounce was generated) which will improve the precision, realism and quality of both effects. This should translate into higher quality indirect lighting that is more in line with the reality of each scene, and more precise and better tuned reflections.
  • The reflections now render at full resolutionwhich will give them a better sharpness and a higher quality compared to insane mode, where they already looked amazing, but without incurring the classic problem of “mirror” mode, since it will still perfectly differentiate between matte surfaces and reflective surfaces.
  • Lighting physics improvements, which will make it no longer necessary to resort to techniques such as ambient occlusion to generate realistic scenes where a large number of objects of different sizes concur. The difference this can make is huge, especially indoors.

With RT Overdrive mode activated Cyberpunk 2077 will work with a total of 635 lightning operations per pixel, which is more than double the amount used in insane mode. Obviously this will have a significant impact on game performance, so it will be essential to compensate by resorting to DLSS2 or DLSS 3 in case we have a GeForce RTX 40. In this case, frame generation will also play a key role when it comes to to improve fluency.

NVIDIA has also confirmed that the game will be optimized to take advantage of technology Shader Execution Ordering (SER), which is exclusive to the GeForce RTX 40, and which can significantly improve performance. I look forward to testing the game with different GPU settings when this patch is released, and I will post a detailed article to tell you what you can expect if you enable RT Overdrive mode.

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