Motion blur is a controversial topic in the gaming space, but outside of gaming is generally accepted as a valid technique in film, TV, animation and so on. What makes motion blur in gaming unique, and contentious? What makes it different from other versions of motion blur? Today, I’m gonna walk you through all of that, so by the end you’ll have a solid idea of what motion blur actually is.
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What Is Motion Blur?
Motion blur in general refers to the visual blur that is added to moving objects. If you wave your hand in front of your face, you’ll see some motion blur, even if you aren’t doing it particularly quickly. Your eyes add motion blur pretty naturally.
When seen in film and live action TV, motion blur is generally a result of camera shutter settings, post-processing, or both. In animation, it’s just…drawn in. Sometimes even stretched in, in the case of 3D animation that’s attempting to imitate 2D animation styles. In any case, the goal remains the same: to simulate that same motion blur that your eyesight perceives but that needs to be recreated in art.
How Does Motion Blur Work In Games?
So, motion blur has to work differently in video games, just by necessity. Video games are rendering the world frame-by-frame, and that’s fundamentally way different than how your eyes or your camera perceives the world around you. In games, motion blur is meant to make in-game motion smoother and more convincing, and serve to hide the fact that you’re seeing in frames per second.
Great implementations of motion blur can feel this way, but unfortunately not every implementation of motion blur has been “great”. And even the good ones still aren’t perfect. Let’s dive into some specific examples.
Motion Blur Techniques Explained With Examples
Frame Buffer Accumulation Motion Blur
Video Example of Sly Cooper with and without this form of motion blur enabled (disabled through mods). Look at the improvement!
First, let’s talk about the version of motion blur that made it infamous: frame buffer accumulation motion blur, also called PS2 motion blur. This form of motion blur was popular on the PS2 and consoles of its generation because it was a relatively lightweight technique, only requiring rendered frames to linger at lower opacities to produce a motion trailing effect.
The problem is, this motion blur effect was applied to the entire screen at once, and resulted in motion blur in many games feeling distinctly artificial, sometimes even a little nauseating. This effect is fortunately not seen very often in modern games, but it isn’t the only unwanted version of motion blur that exists out there.
Camera Motion Blur
Video Example of this technique in Team Fortress 2, running on my own PC. The effect is more pronounced at 60 and especially 30 FPS, but even at 120 FPS it’s disorienting.
Camera motion blur is one of the more infamous modern motion blur techniques. This works by applying motion blur to in-game camera movements, blurring objects further away from the player’s camera while keeping close objects in focus to simulate smoother movement. While this version of the technique isn’t nearly as bad or disorienting as the frame accumulation method, it still suffers from its own problems.
My main issue with camera motion blur can be seen in the video example I embedded up above, enabling the option in Team Fortress 2. While having radial motion blur for things like rocket jumping feels amazing, having motion blur applied to all fast camera motions immediately cuts down on the readability and reactability of the game. Against other skilled players who can kill you in a matter of seconds or less, this motion blur implementation feels like a liability.
Per-Object Motion Blur
Video Example of this technique in Crash Bandicoot 4, running on my own PC. Note how Crash’s spins and general jumping animations are more convincing with this than enabled than without.
Last but certainly not least is per-object motion blur. Per-object motion blur is…well, what it sounds like. It applies motion blur effects, but only on moving objects. The exact implementation will depend on game engine and artist intent, but those general rules should still be followed. When applied to player characters, enemies, and NPCs, per-object motion blur can make smooth animations look even more convincing.
Why You Should Enable Motion Blur
While per-object motion blur isn’t perfect, it’s still pretty good. Without the risk of radial blur actively impeding the gameplay experience, per-object motion blur just serves to imitate motion blur as we already perceive it- on fast-moving objects, not our entire field of vision at once. The performance cost isn’t usually that high, either, but I would hardly consider it a priority setting, especially not in a competitive first person shooter.
Unfortunately, with some games, you run the risk of only being able to enable or disable multiple forms of motion blur at once. As nice as per-object motion blur is, there are games that bundle the accursed screen blur right alongside it, and don’t give me an option to enable just the per-object blur. In cases like this, I’m often pushed to disable the option, especially if I notice it impeding my gameplay in any way.
Why You Should Disable Motion Blur
If the only version of motion blur supported by your game of choice is radial motion blur or, god forbid, frame buffer accumulation motion blur, you’ll most likely want to disable it entirely. Even on occasions where the visuals are enhanced the presence of these heavy-handed motion blur techniques, the resulting cost in visual clarity during actual gameplay is way too high to be acceptable, especially in first person games.
Other version of motion blur should be applied on a case-by-case basis. If you’re hurting for performance, you definitely shouldn’t be turning up motion blur-related graphics settings. However, if you have stabilized performance for your desired refresh rate, you can consider enabling per-object motion blur if you think its implementation improves your experience.