Trailing Lights - Motion Blur FX.. How to?

dexterbot wrote on 7/12/2004, 10:01 PM
Hi,

I'm working on a car video where there is quite a bit of footage from a camera that was mounted on top of a truck and driven around San Francisco at night.

I wanted to know if there is a way to create some type of fx where the tail lights from other cars look like they trail (similar to the Need For Speed Underground Game when you hit the NOS.. LOL). I hope this makes sense. I wanted to speed up the footage and the make it seem like it's going real fast and the lights from other cars will leave a trail.

I don't recall whether I have seen this in any of those import car movies such as Fast and Furious and such but I would really like to try something like it. I've tried using two tracks of the same footage offset by a second with tons of blur on one of the tracks but it does not looks smooth at all.

Any help would be greatly appreciated.

Comments

Grazie wrote on 7/13/2004, 1:44 AM
dexterbot - As you hadn't got a response so far I thought I'd have a chat with you .. .

.. it's ok, nobody else is listening ...

Now I may be totally wrong here but I think you are into the realms of Post-Modernist logic .. let me explain . . well as best as I can .. Post-Modernism, in one sense, disregards that which has come before . . . problem here is that what you have requested appears to want something that has happened to appear as though it DID happen. Meaning you didn't hold the shutter open to get that trailing light sensation/effect . . now that you've "seen" this done elsewhere you, quite rightly, believe that this is an effect that one can imitate in post .. yeah? Still with me? . . But for the life of me I really can't see how one can do this. Just because you've seen it on something would make you think you can indeed do this in post-prod. Well, you/we can do heaps and heaps in post .. granted. I don't think this is one of them.

All we have are millions of separate images to apply an FX to. Taking your project as case in point, how would you suggest we take a tail light trailing around a corner? How would we bend it and keep the rest of the "space" unbent .. as it were? Bezier cutaways . . ppppooargghh .. lotsa lotsa work . .. if even possible . . .

Oh, the Post-Modernist thing/reference? It is at times like this when I think that some basics are needed to be understood - and to do this one needs a sense and understanding of what has occurred or prior! . . Hey, hands up here I do the same . . .

. .now I bet someone is gonna knock me off me soapbox now and come up with a way of doing what you've asked .. if that is the case, then we all win!

Nice question .. . I nearly got very very busy with V5 just to see .. .

Best regards,

Grazie
farss wrote on 7/13/2004, 3:22 AM
What you are trying to simulate is afterglow or image retention. You see it happen in the older CMOS image sensors and even to some extent in our eyes.
So just using motion blur isn't going to cut it, you only want trailing images of the highlights, just motion blur is going to make everything blurred. So I'd start with lots of motion blur, then I'd use a mask to separate out just the highlights, maybe with some degree of chroma filtration so you get say just the red tailights. So you want to endup with a track of just the trails. Then you composite that back onto the original footage without the motion blur or with less blur to compensate for the speedup.
Certainly not something you can do with just one FX although it's probably just one button on the desk of a high end system that's no fun at all. The great thing about Vegas is seeing just what you can do with the basic toolkit, you've got the same building blocks as any of the high end gear without the pricetag and you get to decide how it'll look.
Grazie wrote on 7/13/2004, 5:44 AM
I knew that! . . I was just out buying some stuff when I thought about the "layers" options and then it hit me too . .. and yes working this out within Vegas will be a lot more fun too!

Grazie
TomE wrote on 7/13/2004, 6:52 AM
Just a quick glance at this and the first thing that popped into my head was the Wax plugin 2.0c . There should still be the pixel stretch option available (which was alo in the original plugin pac) If you worked with that and used masks (either made in Wax or with either a cookie cutter or the bezier tool in V5) then you can isolate the area that you want to stretch. This will give you more dramatic streaks , I think.

-Tom
farss wrote on 7/13/2004, 6:55 AM
One thing with motion blur, seems the default is symetric which doesn't give a quite realistic blur ( it looks x frames forward and backwards) on some things, easy enough to change it to asymetric in project properties, took me a while to notice that one.
Lawrence wrote on 7/13/2004, 7:33 AM
One way is to export it to TGA.
Work on the images with a Photo Editor to gives you the blur effect.
PIXL has a filter to do it. You may have to add frames.
Import it into Vegas as sequence of images.

This can also be done with a Video Paint program.
Grazie wrote on 7/13/2004, 8:44 AM
Hey Guys! There's a erson who is GETTING rendered trails . .as a FAULT! . . go read the post . .and think on . .

ANother idea here .. . is it posible to muck about with CAPTURE . .to induce a tpye of smeary/trial thingy . . only a thought . .'cos if this person is getting renedered stuff trailing then that might be uselful here .. but on another tack using actual CAPTURE at some silly frame or what ever . .I dunno . . it miyht provide somewthing else too .. ooooo I'm starting to get really interested . . I think we might be onto something . .. hmmm....

Grazie
RichMacDonald wrote on 7/13/2004, 9:21 AM
I'm stuck without my Vegas right now, so I cannot search FX for you. However, roughly it seems like you have two steps: (1) Separate the tail lights from the rest of the footage. Try some kind of brightness filter which lets the bright areas through and turns the rest of the footage into alpha. (2) Adding the trail to the lights. Maybe motion blur does it well enough, but isn't there some filter which "echoes" the picture by delaying it one or more times and overlaying with the original. If you set the delay to something very small, you might get a nice trail. Probably include some blur so you don't see a series of edges on the echoed footage. Now you can just take the result and place it in front of the original footage, with an appropriate blend.
Grazie wrote on 7/13/2004, 9:26 AM
RMD .. EXCELLENT! .. I really think you are onto something PAL! .. . I was thinking also of letting the "overexposing or C/King produce a Trail-Blazer as it were .. using that as a mask . .
Grazie
dexterbot wrote on 7/13/2004, 9:54 AM
Wow.. thanks to everyone for their response. So much information and so many things to try. I think a couple of points here and things that I've tried so far. I did try the motion blur then use a cookie cutter to mask out the motion blur for the center area where I want it to be sharp and look normal. That didn't quite work as well as someone pointed out, the blur is even distributed on both sides when I am really after a distorted look.

I really loved Grazie's answer! :) Very amusing...

In any case, again, thanks to all and I'll try a few of the suggestions above. I'll check out the wax plug-in. I totally understood that this is probably not just a filter but may be a bit complicated and would require several track layers with different filters to get the look which I'm prepared for such complexity. :)
JohnnyRoy wrote on 7/13/2004, 10:26 AM
Pixélan SpiceFILTERS has an effect called StepMotion that does ghosting and other time-delay motion effects. Since the taillights are red, perhaps you can use the Secondary Color Corrector to isolate them and use that as a mask for only applying StepMotion to the taillights. You could try it using the SpiceFILTERS demo.

~jr
Grazie wrote on 7/13/2004, 10:29 AM
.. of course you could go back and reshoot it with the shutter open .. ahuh?

.. . Thanks for your recognition on the . .er .. funny bitz!

Grazie