Hello, we are Andrew Lauritzen and Ola Olsson, rendering engineers who work primarily on shadowing in Unreal Engine 5. Since we started working on UE5, our focus has been on Virtual Shadow Maps (VSMs). VSMs are designed to pair well with Nanite’s virtualized geometry and efficiently render accurate shadows ranging from small geometric detail near the camera all the way to the horizon.

In this post, we’ll cover some of the details of how Virtual Shadow Maps are used in Fortnite Battle Royale Chapter 4, with a specific focus on recent technical improvements as well as content considerations. VSMs were designed specifically with Nanite in mind and integrate tightly with the Nanite rasterization process; in many cases, optimizing shadows and Nanite performance are directly related. Therefore, we recommend reading the Nanite in Fortnite Battle Royale Chapter 4 blog post before continuing, as many of the techniques mentioned there are as important—or in some cases primarily for—Virtual Shadow Maps.

https://www.unrealengine.com/en-US/tech-blog/bringing-nanite-to-fortnite-battle-royale-in-chapter-4