After Epic released the UE5 technology demo at the beginning of 2021, the discussion about UE5 has never stopped. Related technical discussions mainly centered on two new features: global illumination technology Lumen and extremely high model detail technology Nanite. There have been some articles [1 ][2] analyzing Nanite technology in more detail. This article mainly starts from the RenderDoc analysis and source code of UE5, combined with some existing technical data, aims to provide an intuitive and overview understanding of Nanite, and clarify its algorithm principles and design ideas, without involving too many source code level Implementation details.

Lumen is UE5’s GI system, it is different from the traditional real-time GI which only includes the contribution of indirect diffuse reflection. It also includes indirect diffuse reflection and indirect highlight, providing a new set of complete indirect lighting. Lumen supports both hardware-based RTX and software-based Trace algorithms. The starting point of this article is that Lumen GI uses the process, algorithm, and data structure analysis of indirect diffuse reflection part based on software Trace to understand the basic principle and operation mechanism of Lumen from a macro perspective.

The core of Lumen includes the following parts:

Today, we will share some knowledge points related to resource memory leak. A memory leak is the most common issue that we continuously see and also are afraid of. What is the reason behind it? Because we can’t predict the extent of the leak before we locate the leak bottleneck, we had no idea whether it will burst out at a certain moment on the line. We have received feedback from developers that their players had no problem playing for half an hour, but they would get more and more stuck after 3 to 4 hours of playing, which they never expected before. How can it be solved? Today’s sharing will answer such questions.

UWA’s GOT Online-Assets report has a resource occupancy trend chart. If there is a rising trend like the one below, you must pay special attention.