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What about motion blur?

16 posts

Sonic Ether#

What about motion blur?

I think that a motion blur could make things look great. The only thing is that I couldn't really imagine how it would be done but here are my ideas.

A motion blur is a combination of two frames. So, if one frame was:

0

and the next frame was

0

then the result would be a blur between the two zeros

0-0

Sorry for the crappy dash, but that's my motion blur.



So, would this be somthing you would put into a superscope that you wish to motion blur by changing the colors based on the behaviour of the scope? Or would it be possible in a Dynamic Movement? I'm guessing that it would requre somthing like AVS takes like a variable of an image and somehow blurs it with the frame after the taken image. Does anyone have ideas?
gaekwad2#
To get good motion blur by blending frames you need extremely high framerates, otherwise you'll only get ghosting.
Sonic Ether#
How could you blend frames like that though? There's got to be a simple way to do it, or at least fake it.
StevenRoy#
This sounds a lot like something I've done a few times, by creating an empty Effect List with the input mode set to "50/50" and the output mode set to "Replace". This creates a blending effect much like what you seem to be describing.

Of course, you can do the same thing with the input mode set to "Adjustable"; it'll probably be slightly slower, but you can control the strength of the effect.
Tuggummi#
I've done it a couple of times, with multiple dynamic movements. Though they were radial zoom blurs, but the same method could be adjusted for motion blur.

It's a really slow method though.

Examples from two of my packs in the zip.
eheiney#
Oooh, Faster than light! I still love that preset, it's so simple but the result is fantastic. 😁👍
Sonic Ether#
Originally posted by StevenRoy
This sounds a lot like something I've done a few times, by creating an empty Effect List with the input mode set to "50/50" and the output mode set to "Replace". This creates a blending effect much like what you seem to be describing.

Of course, you can do the same thing with the input mode set to "Adjustable"; it'll probably be slightly slower, but you can control the strength of the effect.
PERFECT!! Thanks SO much. This is just the effect I was going for! You're awsome.
Tuggummi#
Hmm, then i have a completly different concept of what "motion blur" is 😱

I was thinking the motion blur effect of image manipulators, ie. photoshop. Couldn't even imagine you wanted something as simple as a 50/replace effect list 😛
StevenRoy#
Yeah, there's a "directional" motion blur (like Photoshop has), and then there's a "temporal" motion blur. It's easy to confuse the two, especially since "motion blur" usually refers to the former.

In fact, I'm not sure "blur" is even accurate in this case; "blend" might be a better word. "Motion blend".
hornet777#
LOL, Tugg: the inconsistent nomenclature is spread throughout DSP; its a mess trying to communicate it....
jheriko#
How about 'physically correct' motion blur? Its prolly the easiest since they give you a fadeout to start with... which is mostly what motion blur is 🙂

Now using the effect list with the 50/50 blend trick just does a special type of fadeout

new=.5*old

i.e. it halfs brightness each frame.

A cheaper and fps independent way to do this is with a color modifier:

init:
lasttime=gettime(0);

frame:
dt=gettime(lasttime);lasttime=gettime(0);
opt = pow(.5,30*dt);

level:
red=red*opt;green=green*opt;blue=blue*opt;

This gives a reasonably accurate approximation to the fadeout acheived by halving the color 30 times a second (like the effect list trick would work running at 30fps).
gaekwad2#
But real motion blur doesn't fade out, you'd have to average framerate/simulated_shutter_speed frames.
jheriko#
Originally posted by gaekwad2
But real motion blur doesn't fade out, you'd have to average framerate/simulated_shutter_speed frames.

On a camera I agree that it is related to exposure time... but I don't think the eyes work in quite the same way. Afaik they recieve a continuous stream of data (photon interactions with eye stuff), and they continually update based on it, blending with the old data, much how a fadeout with no clear every frame works...