UE4 — TemporalAA vs FXAA

A comparison of the two methods and suggestions for improving TemporalAA

Using Unreal Engines’ deferred renderer, you can choose between TemporalAA(TAA) or FXAA as your Anti-Aliasing(AA) technique. Both both of them take a different approach and return a different result.

This article takes a look at both of them. And on top of that, tells you how to improve TAA’s quality!

Overview

To give you an idea, here is the same scene rendered with: No AA, FXAA, and TemporalAA (click to zoom):

No AA

FXAA

TemporalAA

FXAA

Fast approximate anti-aliasing (FXAA) is a popular AA method and requires only little amounts of computing power. This technique results in rather sharp images.

The downside: jagged edges and flickering are possible.

TAA

This technique is the engine’s default one. It compares multiple frames and blends them. This rather new technique aims to produce softer and photorealistic images.

Its performance impact is low but not as good as FXAA.

As good as this sounds, TemporalAA has two big problems: ghosting and blurriness.

What is ghosting

TemporalAA samples are spread across multiple frames. When these frames combine incorrectly, ghosting appears.

Here is an example:

Notice the artifacts on the right of the player. It seems like a ghost is following the character-hence the name: Ghosting.

Improvements

Unfortunately, you can not (yet) get a perfectly sharp, unghosted result in the unreal engine using TAA. But still, there are some things you can improve via the console or config file:

1. Use the new algorithm (Only >= 4.26): r.TemporalAA.Algorithm 1
2. Lower the samples count to achieve a sharper image: r.TemporalAASamples 4
3. Low values = blurriness and ghosting | high values = jittering r.TemporalAACurrentFrameWeight 0.4

Conclusion

Which AA method you will use in your game is up to your taste. Each of them comes with up and downsides. Although it seems that most people-developers, and players, dislike the temporalAA’s blurriness and ghosting.

Do you want to learn more about game development?
This might be interesting too:

UE4 Tick Events and Alternatives

UE4 Blend Nodes Cheat Sheet

UE4 - Creating an Interactive Minimap | Part1

Originally published at https://gameinspired.substack.com.