Create ultra SloMo, might this work?

farss wrote on 9/2/2006, 4:54 AM
Just a random thought while burning and capturing.

Shoot at fastest possible frame rate with static background and locked off camera.
Use difference mask to extract moving subject.
Render out as image sequence.
Now at 1% slomo you need to create an addition 99 frames between every 'real' frame.
Vegas attempts to do this using interpolation but not using tracking and well software to do that is expensive and doesn't plug into Vegas.
So why not use WinMorph, it's going to be tedious work but if you're short on funds and long on time you might be able to pull off some amazing results.
Once you've built all the addition frames for the image sequence recomposite them back onto the background using Vegas.

I haven't tried this myself so I'd seriously suggest doing a short test before wasting hours on it. Just that I saw another post saying that there was an AE plug that could pull good SloMo at 1% and well they must be doing something like this.

Bob.

Comments

DJPadre wrote on 9/2/2006, 10:09 AM
err.. well if ur shooting at faster frame rates, ud natively have slow mo footage at teh acquisition level... shoot at 60fps, output to 24p.. voila, instant slowlo at 2.5 times slower than real at full res.. now this is possible with a HVX....

ok... electronically..
shoot progressive scan.. the higher the res, the beter off you'd be.. then shoot with a pulldown service.. 2:3, 2;3;3;2, or 2;2 i ur in PAL land..
Now by res i dont mena hd... coz its temporal resolution of 540 ACTIVE lines doesnt work as well... reason being is that your delaing with interalced.. ideally.. 720p or 1080p

those pulldown frames are then used as the interpolation reference... so slowdown progressive scan at 50%, and u SHOULD have perfect slowmotion... i know i do... and its barely noticable that its done electronically... , and doesnt flicker like interlaced footage can... then again, flicker is causd by incorrect shutter speeds mostly with interlaced footage...
This is at the time of shooting of couse.. then slowling down that slow shuttered footage..youre causing that shutter to slow down... even more... causing that visible flicker... couple that with the newfound interlace scanlines recently created by half res reference frames/fields.. and voila.. instant strobe light...
Theres more to it, but im too tired...

OKies, afew tips.. shoot wth a FAST shutter.. u want as much detail as possible.. slow shutter means motion blur.. u dont want that on slow mo...

Use the supersampler in vegas.. if uve ever used audio oversamplng techniques, this is pretty much the video equivalent

dont zoom in too far... even though your DoF will be MUCH shallower and look better.. ur cameras stability will start to show its weaknesses.. if shooting handheld, then try go as wide as u can.. slowmo can hide SOME shake, but i wouldnt rely on it...

there is a program by dynapel called slowmotion. IMO, its as good as Vegas with supersampling cranked to 8...

in vegas to get a perfect slowmo, i would recomend shooting with the above methods.. BUT when slowing down, do it in steps, while rendering out to uncompressed AVI so as this way, u dont compromise the image...
OK, got a clip at 100%... how fast is the subject going?? really fast?? or just average?? if its REAL fast, slow it to 90%, suspersample to 5 or 6, interpolate while rendering to uncopressed.. still too slow of course.. but thats ok.. moving on
go back and reimport new clip...
now slow THAT newly slowed clip done to 90%... this will bring your new render down to 80%...
next time, it will bring it to 70, 60 and so on and so forth..

why do this??

well.. think about it.. the more frames u have, the more accurate ur sowmotion interpolation will be..
by slowing it down in steps.. ur offereing the render engine more refence frames for its interpolation. in turn, making it smoother as the accuracy is more precise due to the shorter distance between each reference frame..

now couple this with your multiple renders to uncompressed with supersampling, and u SHOULD be able to bring a superfast clip down to abotu 3% and see it FLOW.... not stutter...

I do this all the time.. and yes its tedious, but the results cannot be beat..


Spot|DSE wrote on 9/2/2006, 11:04 AM
Bob, if I had to go THAT slow, I'd just use Twixtor in AE.
vicmilt wrote on 9/2/2006, 11:25 AM
Bob -
why (curiousity) do you need such incredible slow motion??

(are you considering a career in politics?)

v
SimonW wrote on 9/2/2006, 11:28 AM
Twixtor has its moments, but it still requires a lot of work to get really good ultra slow motion with it that doesn't have weird morhping backgrounds etc.

Now, I haven't tried DJPadre's technique, but I will in a moment.

What might be worth doing is combining it with line doubling slow motion. Vegas can do this, but only it seems when it feels like it!

So for the moment us AE. Take interlaced footage shot with 1/100 or so shutter. Then time stretch it by 200% and render out. Yeah, you lose resolution, but with a really good camera you don't notice so much. Now try DJPadres method. I'm going to try it in a sec.
Spot|DSE wrote on 9/2/2006, 11:43 AM
I've done the line-doubling slow motion, search the forums you'll find a recipe I gave Grazie perhaps 2-3 years ago.
Twixtor and Combustion both give me better results if I'm going beyond 75% of original speed and need good detail. Line doubling/offsetting by half a frame does pretty good too, but Twixtor and Combustion each have some sharpness they bring to the image I can't quite get in Vegas.
I too, will need to try both mechanisms using DJPadre's technique.
SimonW wrote on 9/2/2006, 11:47 AM
Okay, the technique works. But it doesn't solve the problem of horrible motion blur.

farss wrote on 9/2/2006, 3:03 PM
I don't need this but others were talking about how to do it, how to get a 1% slomo and how well other tools can do it.

Obviously there's only one way to do it right, use a high speed camera. There's simply no way that any tool in post can take footage shot at 60i of a bullet going into a light bulb and make it look like footage shot at 1000fps.

However for certain kinds of cyclic (as opposed to one shot) events there maybe ways to fudge it so it looks very good.

The technique that I was proposing is effectively rotoscoping however fairly simple to do rotoscoping. Between the frames that you do have (assuming you shot with very fast shutter speeds) a morphing technique could be used to do the tweening.

Assuming the event is truly cyclic (say moving machinery or someone running on a treadmill) there's another technique that's used in other fields.

If you've ever used an industrial strobe light then you'll know what I'm on about. With these things you can go freeze a moving object and by slowly changing the strobe speed produce a perfect speed ramp. In this case your eyes are thhe camera but you can use the same technique with a camera.

With the strobe light it might be flashing once every 100 revolutions and at the same time of every cycle of the machine, hence it appears stationary. As you ever so slightly alter the strobe rate what's happening is the 'image' is being taken at 100.001 revolutions. The slight offset causes the stobe and the position of the object to drift over time producing super slomo.

Now using a video camera you'll have serious issues trying to get a frame rate that's 100.001 of anything! However shoot enough footage at a very fast shutter speed and eventually you'll get enough frames to give you the required frame sequence to cover one revolution. You'll need to sort these by hand of course and that again will be time consumming but hey it's very cheap compared to renting a high speed camera.

Is this really useful. I don't know, maybe someone might find it usefull. It'll only work for cyclic events, like I said rotating machinery or perhaps a very tolerant subject running on a treadmill. Certainly useless for someone diving into a pool!

Bob.
vicmilt wrote on 9/2/2006, 9:22 PM
Totally unrelated "war story" - skip this if you only want to learn something -
I was working on a campaign for Schweppes Gingerale. The gag was that we wanted to macro zoom into the top of a glass of freshly poured gingerale to see the bubbles in super Slow Motion. This for a later effect to be added where the bubbles morphed into a ballet dancer.
All this was way before computer technology, so it had to be "real".
Big Bucks - we flew one of three "super high-speed 35mm cameras in from LA. First class ticket for the highly trained Assistant Cameraman plus hotels, etc. PLUS a first class ticket for the camera (yes it sat up front). Plus, of course the rental, and scads of 35mm film stock to literally burn through.
Now to get enough depth of field on the macro shot with a 25 to 250mm zoom, I had to stop the camera down to f22. This coupled with the super-high shutter speed required to get the 500 fps necessary to slow down those bubbles required a LOT of light!
So I pushed 5 10k spots in a semi-circle around the glass, turned them all on, and took a meter reading - it worked, but it was HOT.
OK - we'll start the camera, then turn on the lights, then do the zoom.
I did three snap zooms, in and out, with a zoom bar and the second the camera ran out of film (less than 30 seconds) the gaffer flipped off the lights and the grip hit the soda glass with a huge CO2 fire extinguisher!
The butcher block that we had put the glass on, was ON FIRE - a lot!
Big scramble - and it would have been funny if it wasn't costing about $5k an hour to shoot.
Ended up putting the glass on a 1/4" piece of steel painted grey with engine paint.
Oh yeah - the shot worked - the effect worked - and the campaign for "Schweppervecence" ran for about a year.

end of story.

v
ps - am I out of line to reminisce like this??
Serena wrote on 9/2/2006, 9:33 PM
Out of line? No way Vic! Love those stories.
DavidMcKnight wrote on 9/2/2006, 10:02 PM
Heck no, Vic! Reminisce all you want.

Better yet, let's make a documentary of your life and times, eh?
farss wrote on 9/2/2006, 10:47 PM
More Please.
TShaw wrote on 9/3/2006, 8:26 PM
Vic, I think we can all learn alot from your war story!

Please post more!

Terry