Almost five years after the last series entry, we finally have some concrete information about the new Forza Motorsport coming next year. While the eighth game in the series takes the number from the title, the presentation was all about numbers: 4K resolution and 60 fps with real-time ray tracing, double the frame rate shown in the 2020 teaser. Running games at 4K 60fps with RT is a tall order, even for high-end PCs, so how can this be done on Xbox Series X?
To find out, we took a look at the two teaser trailers released so far – which, according to Microsoft’s blog, were shot on PC but “also tested on Xbox Series X for the same visual quality” – curious.
Analyzing the footage reveals a few telltale signs of optimizations designed to give the GPU headroom to enable in-game RT — starting with resolution and image quality. Previous Forza Motorsport titles have focused on native resolutions with 4x MSAA, but the new trailers show aliased geometric borders that aren’t consistent with multi-sampling. That suggests we may be looking at a cheaper anti-aliasing technique. Likewise, the game doesn’t seem to focus on native 4K, with the number of pixels going up to 1080p in some scenes, but up to 4K in others. There are also instances where recently revealed objects on the screen have a telltale pattern of pixels. These signs can be explained by some level of image reconstruction, variable speed shadowing (VRS) or perhaps TAA.
These techniques make 4K 60fps with RT a more realistic target, but maybe that 4K should have an asterisk next to it. This is nothing new for the console space, but it is certainly a new approach for Turn 10 and Forza Motorsport.
The trailers also point out some of the settings the developers could use to make real-time ray tracing more affordable. I suspect that the Turn 10 team chose a specific type of RT reflection to keep the computational costs down – namely by using coherent mirror-like reflections instead of more subtle and realistic glossy reflections. This has an excessive impact on performance – when testing the Ghost Runner game on PC, I found that using mirror-like rather than glossy reflections saves 10ms on an RDNA2 video card. that is 60 percent of the frame time of a 60fps game – a huge amount. There is some evidence that this RT setting is used in the five-minute trailer, where materials show glossy, mirror-like reflections or no reflections at all.
Interestingly, though, the other trailer — the one-minute sizzle reel — looks very different. It has a lot of diffuse reflections, which Turn 10 recently confirmed to be the result of ray-traced global lighting (and obviously better quality RT reflections) in repeats, the garage, and photo mode. That’s great from a technology standpoint, but to label it as “in-game 4K visuals” when we talk about replay cameras feels a little opaque to the audience, especially when the other trailer that is based on gameplay fidelity shows no RTGI and less impressive reflections while similarly labeled. It also raises the question of the PC version – will those with enough powerful rigs also be able to enable higher quality RT GI and RT reflections in good gameplay? Hopefully we don’t see an arbitrary throttling here, but that’s what we saw in Forza Horizon 5, which disabled RT in-game – even if you have the hardware to handle the extra GPU load.
In addition to the strategies to enable 4K 60fps with RT, the demo also shows Forza changes that seem to take advantage of the newer hardware found on PC and Xbox series consoles. A big change is a dynamic time system, which requires the game to re-light up in real time – something that would have been a huge feat on previous consoles. Likewise, there’s a big boost to the details along the track, with more spectators, objects and even real 3D trees with individual branches and real-time self-shadows. Zooming in on a shot of a cone road reveals upgrades to the shadow model, which shows much more material variation. While road and cone had a similar texture in FM7, each is now shaded differently, and the cone’s plastic even contains a simulation of subsurface scattering; the thinner parts of the plastic allow light to pass through. Given detail differences like this, I’m very curious about how other aspects of the game are detailed and shaded up close, such as crowds or pit crews.
Clearly there are clear and meaningful image quality upgrades here to fit a tentpole release in 2023, alongside clever optimizations that make 4K 60fps with RT reflections conceivable for PC and consoles.
However, a few questions remain regarding the Xbox Series version of the game: does it exhibit similar picture quality and performance to the PC version, or are bigger compromises required? Likewise, the Xbox Series S version is specifically described as having real-time RT, so what does that look like and how does it work? It will be fascinating to see those questions answered as we learn more about the game.