Need help on a motion blur effect (if it even is motion blur)

video6000 wrote on 3/6/2003, 11:24 AM
I need help on a certain effect. I've seen it in some movies, Im not sure if it has to do with motion blur, or a way to adjust it, but whatever, let me explain what I'm trying to do.... Do you know on really old photo camera's...if you hold down the shutter button every single little move gets shown, and if you hold it too long and move the camera too much evrything will get smeared. Like if all the frames do not get refreshed and just stay there, but new frames comes rigt over it. If you don't understand what I mean, please reply. Thank you

Comments

Chienworks wrote on 3/6/2003, 12:54 PM
Are you looking for a sort of motion trail behind the objects that move? Kinda like in Star Trek when they hit a wormhole and everyone's movements get smeared?

In the big budget movies they use lots of processing to get a nice smooth feel to this effect. In video one of you biggest limitations will be the frame rate and that the frames are discrete stills. I've done a cheep simulation of this effect by placing the clip on several tracks and offsetting them all by a frame or two. The track that starts first will be set to 100% compositing level. Each subsequent track will be set slightly lower so that the motion fades out as it gets older. The more tracks you use the better the effect will be.

I'm uploading some sample ideas to http://www.chienworks.com/media/q-bounce/ ... -1 uses single frame offsets. -2 uses two frame offsets. -3 also uses 2 frame offsets with added linear blur to smooth it out a bit. The .veg files use generated text media. You can easily replace this media with your own video clips.
aboukirev wrote on 3/6/2003, 2:47 PM
Actually, if you have Pixelan Filters for Vegas Video (works with Vegas 4 too), they have TimeStep and MotionStep effects. You can use one of these for a nice ghosting effect.

Alexei
video6000 wrote on 3/6/2003, 6:02 PM
Thank you all for your posts, Chienworks, thanks for your files. aboukirev, I'll check out the filers.

Thanks again!
Paul_Holmes wrote on 3/6/2003, 6:15 PM
Try setting a motion-blur envelope at about 20% to 40% at the points before and after you want it to apply (leave it at 0 elsewhere since on my Athlon 1800 it takes about 1 hour per minute to render). I've just did that in a recent movie during a fast pan and it really gave it that wide-aperture, blurring effect, kind of like a professional movie camera. Might be what you're looking for.
FuTz wrote on 3/6/2003, 8:34 PM
Some kind of a "Bull's eye" sir Holmes! My idea is that it's the closest way to achieve what's video6000 is looking for...
FuTz wrote on 3/7/2003, 8:34 AM
I guess if you want a blur on a **specific subject** in the picture, you'll have to use Premiere/Photoshop or wait 'til Satish comes with his Rotoscopy app...
The only way I see this can be done is frame by frame for now, am I right?
Erk wrote on 3/7/2003, 10:47 AM
Interesting thread. Futz, you got me thinking. I take it you're wondering how to blur the movements of, say, only one person in the frame. You might try placing an identical track above your original, and in the top track cropping out everything except that person/object you want to blur. Make the crop follow that person/object's movement, then apply motion blur per Paul Holmes post. I think I'll try this tonight....

G
FuTz wrote on 3/7/2003, 1:19 PM
Erk: that's exactly that. That's what I meant by saying we ought to use Photoshop (to create a mask if the background is too "diversified"). If the background is kind of "plain", maybe the mask generator would be ok?
Come back to us with your results!