Motion blur all the way down (2022)

The tradeoff of rendering or filming motion blur at finite refresh rates is the audience can move their eyes to follow an object moving around the screen. In real life, that causes the object to become sharp. So, you either need to track eye motion and blur according to relative motion, or do no motion blur at an infinite refresh rate. Neither is practical with todays's technology, so it's always going to look wrong. A good director or game designer will choose shutter rate or render blur according to how they expect the audience eyes to be moving.

Despite the promise of this making visual media feel more real, I can&#x27;t help but feel like, for games, this makes the video games look like a cheap approximation of over-edited movies. For things moving real fast, or real close, or especially with non-ego motion, this all makes sense. But it is over-used for things like &quot;the character turns quickly&quot;.<p>When I snap my head (or eyes) around, I don&#x27;t see a blurry image, I see the new image, and my brain drops the intermediate data. You can test this by looking at yourself in a mirror, focusing on one eye, then another. Do you see your eyes or face or anything blur?<p>Adding blur just delays the presentation of the new view when moving your POV in games. It&#x27;s distracting and unrealistic.

A good overview is in [1].<p>Curiously, before the classic paper on modeling shutter efficiency [2] came out in 2005, all renderers used in VFX production used box shutters. I.e. the shutter opens instantly, stays open for the specified duration and then closes instantly.<p>When you watch movies like &quot;Jurassic Park&quot; or &quot;The Mask&quot; and see scenes with extreme motion blur, that&#x27;s PhotoRealistic RenderMan with a box shutter.<p>The first in-the-wild 1:1 implementation of the parameterization in [2] was done in [3] in the same year the paper came out (hasn&#x27;t changed until today). It was first used on &quot;Charlotte&#x27;s Web&quot; (only the spider character done by Rising Sun Pictures has it as they used [3] for it).<p>Pixar added it a few years later too and went a tad overboard with theirs in [4]. Most offline renderers nowadays have this feature and call it a &quot;shutter curve&quot;.<p>[1] O. Navarro et al.: Motion Blur Rendering: State of the Art (<a href="https:&#x2F;&#x2F;citeseerx.ist.psu.edu&#x2F;doc_view&#x2F;pid&#x2F;fc23fb525cafa8fe68ec84c1eadf85e30090a774" rel="nofollow">https:&#x2F;&#x2F;citeseerx.ist.psu.edu&#x2F;doc_view&#x2F;pid&#x2F;fc23fb525cafa8fe6...</a>)<p>[2] Stephenson, Ian: Improving Motion Blur: Shutter Efficiency and Temporal Sampling (<a href="https:&#x2F;&#x2F;staffprofiles.bournemouth.ac.uk&#x2F;display&#x2F;journal-article&#x2F;5221" rel="nofollow">https:&#x2F;&#x2F;staffprofiles.bournemouth.ac.uk&#x2F;display&#x2F;journal-arti...</a>)<p>[3] <a href="https:&#x2F;&#x2F;www.3delight.com&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.3delight.com&#x2F;</a>, see specifically <a href="https:&#x2F;&#x2F;nsi.readthedocs.io&#x2F;en&#x2F;latest&#x2F;nodes.html" rel="nofollow">https:&#x2F;&#x2F;nsi.readthedocs.io&#x2F;en&#x2F;latest&#x2F;nodes.html</a><p>[4] <a href="https:&#x2F;&#x2F;renderman.pixar.com&#x2F;resources&#x2F;RenderMan_20&#x2F;cameramodel.html#the-shutter-model" rel="nofollow">https:&#x2F;&#x2F;renderman.pixar.com&#x2F;resources&#x2F;RenderMan_20&#x2F;cameramod...</a>

It seems to me that the demonstration is calculated in sRGB space, so with non-linear brightness values and I suspect that most of the unnaturalness of the smear is due to that. To simulate the physics this would need to be done with linear brightness values and only at the end converted to sRGB.<p>(unless some non-linear effects in human visual perception cancel all that out, but it should at least be mentioned if so)

The torus demo is really neat. I think it&#x27;s interesting how high frame rate changes the perception of blur. I&#x27;m using a 240 Hz display and on figure 5 I can&#x27;t see the discrete circles until around 12 rad&#x2F;s. And even at 40 rad&#x2F;s I can&#x27;t see any difference between the traditional and sine shutter options (in motion).<p>I highly recommend 240 Hz if only for the smoothness and low latency of mouse movements. A 60 Hz mouse pointer is really, really hard to go back to.

Shouldn&#x27;t the torus and the latter sphere be partially transparent if they are build from motion blur ? They seems to become opaque again at some point and it feels strange to me.

This gets past trying to simulate a film camera and tries to simulate the human visual system. That&#x27;s useful. Another step towards reality and away from simulating obsolete technology. Shutter-type motion blur may go the way of sepia-toned prints, 16 FPS black and white movies, and elliptical wheels from mechanical shutters.

Ah, I assume this was posted because ambient.garden was just on the front page. Re-reading it now, I think it should really have been 2 articles.<p>I think I still like the first half, it&#x27;s a reasonable dive into the detail of what motion blur is, or should be in theory. The second half is a slightly crazy, extremely condensed explanation of how the shader works for this particular &quot;torusphere&quot; animation based on motion blur. I find that part mainly useful because otherwise the code would be impenetrable at this point, at least to me. In retrospect the transition between the 2 parts feels a bit like jumping into a frozen lake, sorry about that!

Wow, the live comparison demo is wild. When I was following along up to that point, I felt like I &quot;got it&quot; on an intellectual level, but it wasn&#x27;t until I could toggle the motion blur on&#x2F;off that the difference was really apparent!

Wow, watching motion blur all the way down really made me think about string theory, atoms, and how the universe is made for some reason!

Related: Gotta love the ReelSmart Motion Blur plugin for adding motion blur based on the automatic tracking of every pixel from one frame to the next. It&#x27;s not always perfect but still does an amazing job. Sometimes I get experimental and crank the calculated motion blur way past the default value and it looks surreal!

At first I was wondering why the shading of the ball is off - turns out it&#x27;s because it&#x27;s not a ball but a rotating &quot;torus&quot; (orbiting ball)... The ball probably would look better if there was a longer period between the last and first phases, but that could reduce the power of the surprise.

It was noted early in the development of cinema that the required framerate would probably be much lower, if (IIRC) the shutter could be somehow replaced by blending the neighboring frames together, that is the exposure would gradually shift from the first frame to the next.

Motion blur makes sense for films. I have no idea why anyone wants it in a game. The limitations of display technology and of the human eye introduce all the blur I could ever want.

I love thise interactive tutorials. Since the method and it&#x27;s parameters can be changed it would ve interesting to see some form of performance impact.

I want to try this in my pygame game. Any python version of this.

Motion is an invisibility cloak.

Alternative title: Visual proof of the Rutherford model