In September 2023, Scans Factory released a pretty cool tech demo for Unreal Engine 4, called Abandoned Warehouse. That demo had amazing pre-baked lighting using traditional methods, and it did not use Ray Tracing or Path Tracing. So, earlier this month, Scan Factory ported the tech demo to Unreal Engine 5, using Lumen and Nanite. And, as you will see, this tech demo is the perfect example of why UE5 can actually harm games and demos that use incredible pre-baked lighting.
But how do we know that this tech demo did not use Ray Tracing in UE4? Well, this is coming straight from the dev team. As Scans Factory said when asked about whether this pack is compatible with Path Tracing.
“There were no special preparations for Path-Tracing. To be honest I’m not sure what could be useful special for that.”
Not only that but a UE4 game with Ray Tracing cannot run as fast as what you’re about to see at Native 4K on an NVIDIA GeForce RTX 4080. So yes, the UE4 version of this tech demo used traditional rasterized techniques.
So, as we can see in this comparison video, the NVIDIA RTX 4080 can run the UE4 version of the tech demo with 120-190fps at Native 4K. On the other hand, the UE5 version (which supports Lumen and Nanite) runs with 30-48fps. Ouch.
Now the big issue here is that the pre-baked lighting was so good in the UE4 version that there are only minor visual differences between the UE4 and the UE5 builds. And this right here shows why a lot of us loved pre-baked lighting in older games.
With pre-baked lighting, developers can make their scenes look amazing, almost as good as if they used Path or Ray Tracing. That’s why games like The Last of Us Part 2, Uncharted 4, and Assassin’s Creed Unity still look great in 2024. But when developers started using full dynamic time-of-day (TOD) systems, the quality dropped.
To put it simply, the tech wasn’t ready yet when the devs started using full dynamic TOD systems. This is the area that Ray Tracing/Path Tracing can greatly improve. With Ray Tracing, games using a full dynamic TOD system can finally match the visuals of games that used pre-baked lighting. That’s why Ray Tracing/Path Tracing are so important.
Now, if the UE5 version was not using Lumen but relied on the UE4’s standard lighting pipeline, it would be running almost as well as its previous version. So, the problem is not UE5. The performance culprit here is Lumen (which as I’ve said numerous times is a form of Ray Tracing, so it has very high GPU requirements).
In conclusion, games with great pre-baked lighting won’t suddenly look better when developers remaster them using UE5 with Lumen or Ray Tracing. However, games with poor traditional lighting will definitely look better with Lumen. So, Ray Tracing can improve a bad-looking game. But games that already look amazing won’t get much better with Ray Tracing, Path Tracing, or Lumen. Instead, they will look the same but run a lot slower.
That’s also how Ray Tracing and Lumen can make game development faster. Instead of spending a lot of time carefully adjusting every scene, devs can use Ray Tracing as an all-in-one solution. This way, they can achieve amazing image quality in their scenes more quickly.
This is a topic I always wanted to touch and this video was the perfect excuse to write this article. So, there you go!
John is the founder and Editor in Chief at DSOGaming. He is a PC gaming fan and highly supports the modding and indie communities. Before creating DSOGaming, John worked on numerous gaming websites. While he is a die-hard PC gamer, his gaming roots can be found on consoles. John loved – and still does – the 16-bit consoles, and considers SNES to be one of the best consoles. Still, the PC platform won him over consoles. That was mainly due to 3DFX and its iconic dedicated 3D accelerator graphics card, Voodoo 2. John has also written a higher degree thesis on the “The Evolution of PC graphics cards.”
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