Unreal Scene Optimization Guide

Table of contents:

In-Camera VFX Best Practices

There are a number of challenges associated with building an environment that will be used for an in-camera VFX shoot. The two main concerns are: Mitigating these issues requires close collaboration between the Art team and the Stage team.

https://docs.unrealengine.com/4.27/en-US/WorkingWithMedia/IntegratingMedia/InCameraVFX/InCameraVFXBestPractices/

Automated performance testing (access to same spec node over vpn?)

Fog sheets, Depth fade instead of vol fog

Cascade shadow

Merge Actors, LOD

SS effects

Settings, console commands

Basepass: Drawcall

Prepass: Triangles

Perf Camera Insights

Unreal insight: -trace=cpu,frame -tracehost=172.16.200.207

Avoid landscapes with nDisplay → bake to static mesh and split (for culling performance)

Stat fps, gpu, rhi

cull distance volume

instance meshes/dynamic

Reduce Draw Call

Reduce Shader Complexity

Reduce Shadow Cost

Renderdoc

Typical problems, easy fixes (volumetric clouds → texture, volumetric fog → fog sheets)

LOD mgmt

smooth frame rate off

GPU Profiling

The GPU has many units working in parallel, and it is common for it to be bound by different units at different sequences of the frame. Due to the nature of this behavior, it is beneficial to identify where the GPU cost is going when searching for bottlenecks and to understand what a GPU bottleneck is.

https://docs.unrealengine.com/4.27/en-US/TestingAndOptimization/PerformanceAndProfiling/GPU/

UE4 vs UE5

Measuring Performance

In this chapter you'll learn about: The importance of using milliseconds in game development Converting ms to frames per second Basic tools for measuring performance Displaying statistics for each subsystem, like occlusion culling or particles Recording performance metrics and reading them with a profiler If you prefer a video version of this lesson, you can watch it on YouTube.

https://unrealartoptimization.github.io/book/process/measuring-performance/

Shader Optimization

• Reduce Shader Instructions by refactoring code (combine math operations, avoid process heavy operations such as power functions, HLSL)

• Combine Textures

• Mip Map Textures

Unreal Engine Performance Guide

Our one-stop guide to performance with Unreal Engine.

https://gpuopen.com/unreal-engine-performance-guide/

Further Reading

Understanding BCn Texture Compression Formats

The current state of the art in GPU-supported texture compression is a set of seven formats called BC1 through BC7. These formats are used by almost all realistic 3D games to reduce the memory footprint of their texture maps.

https://www.reedbeta.com/blog/understanding-bcn-texture-compression-formats/

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