We're big fans of Digital Foundry's work here at Nintendo Life, and the team's breakdowns of game performance always throw up some interesting findings. The guys are back with some more evidence on how Nintendo has managed to produce such an incredible visual spectacle with The Legend of Zelda: Breath of the Wild - basically, the game dynamically scales the resolution to keep things around the 30fps mark.
While the process isn't entirely elegant, Digital Foundry's Tom Morgan has nevertheless been able to spot dynamic resolution scaling in captured screenshots taken when the Switch is in portable mode (like the one shown above). The results suggest that when the game hits the limit of the system's power, resolution drops to 90 percent on both axes. That means that in portable mode it dips to a resolution of 1152x648 - 81 percent of native 720p in total.
These findings initially seemed to give evidence as to why the game runs better in portable mode than when docked, but Digital Foundry subsequently discovered that the game employs the same scaling when played through the TV as well:
...further investigation confirms that the same scaling tech is utilised when Zelda is docked as well, with a native pixel-count of 1440x810 at stress points, dropping down from its usual 1600x900. Tellingly, this is also a 90 per cent scaling on both X and Y axes, just like the handheld scaling implementation.
It's the same 56 per cent increase in resolution between the two modes, whether the dynamic scaler is active or not, so the bottom line is that Breath of the Wild's increased performance level in handheld mode isn't explained by the game's ability to change its native rendering resolution. The comparatively small bump in memory bandwidth between mobile and docked configuration remains our best theory here. Undocked, Switch runs its LPDD4 modules at 1331MHz, rising to 1600MHz when plugged into the dock. That's only a 20 per cent increase in bandwidth to sustain a 56 per cent uplift in resolution. Meanwhile, both CPU and GPU are tapping into that same pool of bandwidth, possibly causing contention issues.
The discoveries don't end there, though. It has also been found that the Wii U version of the game uses dynamic scaling as well:
As things stand, the dynamic scaler also doesn't explain how the Switch version is capable of outperforming Wii U comprehensively in GPU-bound areas because - yes, you've guessed it - the same scaling technology is also deployed on the last-gen version of Zelda as well. We used Kakariko Village here as an established testing point where performance is poor in order to confirm this. Wii U matches Switch's portable profile, offering up a 1152x648 resolution in these areas.
What's striking about these findings is how well Nintendo has implemented this system; as Digital Foundry admits, this really should have been spotted earlier, but it's so well utilised that it hasn't actually cropped up until now.
While Breath of the Wild isn't without its technical quirks and performance bottlenecks, it's a staggering achievement on a device which is a fraction of the size of a traditional games console - and can be carried around in your bag, to boot. The use of resolution scaling on the fly is just one of the tricks Nintendo has used to hit this goal.