examples of real motion blur?

[QuantumPion]

Are there any games or graphics demos which have an example of real motion blur? By this, I mean the amount of blur is not just a smearing of frames together for aesthetics, but actually calculating the amount of blur based on the current frame rate as a real camera with a shutter operates. So if you are rendering at 30 frames per second, each frame would be blurred based on 1/30th of a second of movement. That way lower frame rate would produce more motion blur to compensate to keep the apparent motion smooth.

 

[antihelten]

I'm fairly sure that normal motion blur already does this. it basically works by measuring the difference in position of a given pixel from one frame to the next, and applying the blur based on this.

Say for instance a pixel moves 1 cm during 1 second, then from frame x to frame x+1 the pixel would move 1/30 cm at 30fps, and 1/60 cm at 60 fps. therefore the pixel moves faster between frames at 30 fps than at 60 fps, and therefore more blur would be applied.

 

[QuantumPion]

I'm fairly sure that normal motion blur already does this. it basically works by measuring the difference in position of a given pixel from one frame to the next, and applying the blur based on this.

Say for instance a pixel moves 1 cm during 1 second, then from frame x to frame x+1 the pixel would move 1/30 cm at 30fps, and 1/60 cm at 60 fps. therefore the pixel moves faster between frames at 30 fps than at 60 fps, and therefore more blur would be applied.

I do not think this is the case. If it were, the amount of motion blur would differ based on your current frame rate, which I don't think it does. Furthermore the amount of blur is often adjustable, e.g. in Battlefield 3. The amount of blur added is arbitrary and is added just to give a smeared appearance to motion. It does not actually model the real, physical blur effect of displaying motion using discrete frames.

 

[gorobei]

which motion blur are you talking about?:

-eye/brain image persistence
or
-film camera artifact from 24 fps pn low iso stock

one is whatever you eyes see and the other is a completely unnecessary visual effect tacked on by render engine coders to make it sound like they are using features/commercials technology.

motion blur is a compromise designed to hide the fact that 24 fps while good enough to create illusion of motion has a ton a artifacts from the time interval(blur, strobing, low iso grain, etc). cgi has to match what the live action plates are capturing on set, so post process motion blur is added. without this you get the harryhousen effect.

real eyeballs work a lot better than film so the amount you would see in real life requires the object to be moving much faster to match the blurs on film or what cg does to emulate film. other than some customized esthetic effects in racing games, motion blur should never be used in realistic first person games(unless your game is trying to emulate a 24 f/s old time movie).

 

[Stuka87]

Any particular reason you are looking for this?

Motion blur doesn't really exist in the real world with our eyes unless the object is spinning very fast. Like the wheel on a car for instance.

 

[QuantumPion]

which motion blur are you talking about?:

-eye/brain image persistence
or
-film camera artifact from 24 fps pn low iso stock

one is whatever you eyes see and the other is a completely unnecessary visual effect tacked on by render engine coders to make it sound like they are using features/commercials technology.

motion blur is a compromise designed to hide the fact that 24 fps while good enough to create illusion of motion has a ton a artifacts from the time interval(blur, strobing, low iso grain, etc). cgi has to match what the live action plates are capturing on set, so post process motion blur is added. without this you get the harryhousen effect.

real eyeballs work a lot better than film so the amount you would see in real life requires the object to be moving much faster to match the blurs on film or what cg does to emulate film. other than some customized esthetic effects in racing games, motion blur should never be used in realistic first person games(unless your game is trying to emulate a 24 f/s old time movie).

A simulation of the latter. Motion blur in film is caused by each frame recording 1/24th of a second of light. What I am looking for is an implementation of this in rendered frames. If a game is rendered at 30 fps, each frame should model the blur of 1/30th of a second of motion. The blur should dynamically adjust based on the actual frame rate (or keep the frame rate locked).

Any particular reason you are looking for this?

Motion blur doesn't really exist in the real world with our eyes unless the object is spinning very fast. Like the wheel on a car for instance.

The reason why I am interested in this is because while fake motion blur in games is annoying and distracting, I am curious as to whether correctly modeled real motion blur would actually improve the appearance of fluidity of motion in games. True, real life does not have motion blur. But a rendered game is not real life either. While a game's rendered frames are not the same thing as a physical camera with a shutter, they are both composed of discrete static images that trick our brain into perceiving them as motion.

 

[KingFatty]

A simulation of the latter. Motion blur in film is caused by each frame recording 1/24th of a second of light.

I think that the shutter speed can be shorter than the frame rate. For example, on a really bright day with fast film, I bet you could use a, say 1/300th of a second shutter speed. Then, you just take one of those shots every 1/24th of a second. Even though you could fit more of those 1/300th shots in one frame or period of time equal to 1/24th of a second, you don't. So the 1/300th speed might also be imposed on you so you don't over-expose the film when it's really bright, and it also is faster to avoid blurring.

 

[QuantumPion]

I think that the shutter speed can be shorter than the frame rate. For example, on a really bright day with fast film, I bet you could use a, say 1/300th of a second shutter speed. Then, you just take one of those shots every 1/24th of a second. Even though you could fit more of those 1/300th shots in one frame or period of time equal to 1/24th of a second, you don't. So the 1/300th speed might also be imposed on you so you don't over-expose the film when it's really bright, and it also is faster to avoid blurring.

I may be wrong, and while that may be physically possible, I don't think that is the case. I am pretty sure movie film (and digital) is exposed in proportion to the frame rate.

 

[gorobei]

I may be wrong, and while that may be physically possible, I don't think that is the case. I am pretty sure movie film (and digital) is exposed in proportion to the frame rate.

no, kingfatty is correct. there is a cylinder inside the camera that has an opening the size of the filmstock on 2 sides that functions as the shutter. while the drive gears will advance and pause the reel at 1/24 sec the shutter can be set to open and close at normal 1/30,1/60,1/220, etc. this adjusts the exposure for lighting.
since 3d cgi or games simulate the exposure, the length is functionally arbitrary and entirely a matter of esthetic choice.

 

[Subyman]

I don't see how the blur being a function of FPS will provide for a smoother experience.

 

[Gloomy]

Do you mean tweening? http://svp-team.com/wiki/Main_Page

 

[soccerballtux]

wave your hand in front of your face really fast

 

[KingFatty]

Anyone know if there's a video showing the difference between something without motion blur and something with motion blur, preferably side-by-side? Maybe at various framerates so we get an idea where it may make a difference and where it may not?

Motion blur kind of makes me think of a way to apply anti-aliasing in the 4th dimension (time). So instead of smoothing jaggies in 3D along geometric dimensions, motion blur smooths "jaggies" in time between one frame and the next? So just as anti-aliasing makes less of an impact as your resolution increases, maybe motion blur makes less of an impact as your framerate increases?

 

[Absolution75]

Killzone2: http://www.guerrilla-games.com/publications/dr_kz2_rsx_dev07.pdf

 

[KingFatty]

Killzone2: http://www.guerrilla-games.com/publications/dr_kz2_rsx_dev07.pdf

Hmm, I like how motion blur adds a bit of excitement to the static PDF image, as my brain link blurring with motion. But, I wonder if there is a video demonstrating this?

Also, it's kind of weird in that PDF example how the motion blur is applied to the gun, but not the hand that is supporting the very same part of the gun. So that seems to defy physics and logic, and I bet it looks wrong somehow. If your hands are swinging a gun, I think your hands should suffer the same amount of blurring as the gun, right?

 

[VirtualLarry]

Motion blur kind of makes me think of a way to apply anti-aliasing in the 4th dimension (time). So instead of smoothing jaggies in 3D along geometric dimensions, motion blur smooths "jaggies" in time between one frame and the next? So just as anti-aliasing makes less of an impact as your resolution increases, maybe motion blur makes less of an impact as your framerate increases?

What about "temporal AA"? I thought that was implemented.

 

[KingFatty]

http://www.anandtech.com/show/350/3