Forums > Videos > Long exposure effect for poi videos.

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polaritySILVER Member
veteran
1,228 posts
Location: on the wrong planet, United Kingdom


Posted:
Finally got round to trying out an effect I thought up, that simulates a long exposure, like you get with a stills camera, but applied to a video sequence. (This footage is from the [Old link])

https://nautilus.homeunix.org/_movies/poi/effect_test.avi


I had to convert the movie to individual frames, run them through photoshop (which took ages), then convert the frames back into a movie. I should be able to automate it though using some unix tools. That would make it a lot easier to use. Would be good for highlighting nice moves like flowers.

The strobing's a problem. I'd rather have a solid line, but that might depend on the camera (I used my digital camera in video mode).


Opinions / ideas?
You aren't thinking or really existing unless you're willing to risk even your own sanity in the judgment of your existence.

Green peppers, lime pickle and whole-grain mustard = best sandwich filling.

MikeIconGOLD Member
Pooh-Bah
2,109 posts
Location: Philadelphia, PA - USA


Posted:
I think it looks awesome. I think its cool even with the strobe. It might even be better than a solid line. Would it be possible to add a fade effect so the trail is only so long and fades out? Let's turn those old bridges we crossed into ashes. We'll blaze a new trail, and torch the rough patches. -Me

HeadSwimGOLD Member
...curiously lost
580 posts
Location: at my PC....obviously!, United Kingdom


Posted:
Nice effect!! I think I have seen something similar on a vid before but can't remember which one at the mo....

What kinda Poi is the spinner using? I need a good set of glow Poi and they look awesome! smile Nothing is easy.......until you can do it!

LazyAngelGOLD Member
Carpal \'Tunnel
2,895 posts
Location: Cambridge UK


Posted:
Yeah looks wicked similar to the effects on 'Dervishly Yers' (see Meenik's videos) Because ActiveAngel sounds like a feminine deodorant

Like sex, I'm much more interesting in real life than online.

'Be the change you want to see in the world around you' - Ghandi

ben-ja-menGOLD Member
just lost .... evil init
2,474 posts
Location: Adelaide, Australia


Posted:
cool effect you could weight the frames superposition value to get a fade effect, also weighting the pixels luminance value to get the trails with the glow/fire and avoid the blur on the arms. you could possibly intepolate the high luminance values for the glow/fire between frames based on the velocity vectors to get rid of the strobing Our deepest fear is not that we are inadequate. Our deepest fear is that we are powerful beyond measure. It is our light, not our darkness that most frightens us. We ask ourself, who am I to be brilliant, gorgeous and talented? Who are you NOT to be?

DuncGOLD Member
playing the days away
7,263 posts
Location: The Middle lands, United Kingdom


Posted:
Nice vid, sounds like a lot of bother tho! I found a setting on my new cam that does that, it's ace biggrin Let's relight this forum love

polaritySILVER Member
veteran
1,228 posts
Location: on the wrong planet, United Kingdom


Posted:
I've been looking through the ImageMagick documentation (a unix tool that can manipulate images from a script), and it looks like I could do a hell of a lot with all the stuff in there.

I'm used to writing complex scripts in python (I've converted yahoo groups archives to unix mailbox or Outlook .eml formats for people before), and to be honest images look a lot simpler than regular expressions.

I could probably mask off everything but the poi heads, and then vary the fades, or number of frames that make up the trail as much as I want without messing up the rest of the image.

I hadn't thought of interpolation, though it wouldn't be the same as having all the color changes there. Video doesn't do justice to the strobe fades of Jon's [Old link]. There are loads of stills on his server that show them better (and a few shots of my cat umm ) You aren't thinking or really existing unless you're willing to risk even your own sanity in the judgment of your existence.

Green peppers, lime pickle and whole-grain mustard = best sandwich filling.

ben-ja-menGOLD Member
just lost .... evil init
2,474 posts
Location: Adelaide, Australia


Posted:
buy a nice 3ccd camera mmmmmmmm 3ccd Our deepest fear is not that we are inadequate. Our deepest fear is that we are powerful beyond measure. It is our light, not our darkness that most frightens us. We ask ourself, who am I to be brilliant, gorgeous and talented? Who are you NOT to be?

.:star:.SILVER Member
Pooh-Bah
1,785 posts
Location: Bristol, United Kingdom


Posted:
pretty colours ubblove

flidBRONZE Member
Carpal \'Tunnel
3,136 posts
Location: Warwickshire, United Kingdom


Posted:
Written by: polarity

had to convert the movie to individual frames, run them through photoshop (which took ages), then convert the frames back into a movie. I should be able to automate it though using some unix tools.






I've used imagemagick quite a bit, I use it for the backend of my photo gallery software. It's good stuff.



I'm not sure how you'd get the automatic masking working thou without either lots of user intervention or mathematics way beyond me. If you're simply image stacking then not only the background will become brighter. Even if you manage to just image stack certain colours (ie the poi heads) then you'd still need to purposely shoot the video with this in mind (ie no colours elsewhere the same, like chromakey).



I beleive that meenik did something similar a few years ago, using a normal video editting package(?)



Written by: polarity

The strobing's a problem. I'd rather have a solid line, but that might depend on the camera (I used my digital camera in video mode).






It'd definately help with more frames per second.

-sandy-BRONZE Member
old hand
716 posts
Location: Bristol, United Kingdom


Posted:
if u want to get thru the photoshop part faster try using the automate batch feature in the file menu. u have to record the actions u want it to perform on every picture first (in the actions tab) then set it to automate batch.
This means you wont have to do each frame individually. look in the help menu if this doesnt make enough sense.
Also if u want to get the trails fading over time try setting a cross disolve over all of them and set the disolve to how long u want the trails to fade over. "Don't do it naked!"

Bender_the_OffenderGOLD Member
still can't believe it's not butter
6,979 posts
Location: Melbourne, Australia


Posted:
does after effects natively support photoshop filters? Laugh Often, Smile Much, Post lolcats Always

*HyperLightBRONZE Member
old hand
1,174 posts
Location: Great Malvern [UK]


Posted:
That's pretty cool! I think you need a better camera to more accurately replay the effect. The strobing is down to the camera rather than the poi. Have you tried decomposing the vid I posted? Maybe that would work better? Cake or Death?

Gal koh pan gannewbie
10 posts

Posted:
very nice effect but I'm more amazed from the poi. What is that? Home made? How? Where? when? what? Anything...

polaritySILVER Member
veteran
1,228 posts
Location: on the wrong planet, United Kingdom


Posted:
After checking a lot of videos I haven't found any that don't have strobing in them. I guess there has to be a break in the video capture, so the image can be written to memory. It's not really noticeable with fire, as the trails fill in, but LEDs are point lights, not area lights, so the gaps are noticable.

A camera probably has to be really expensive to have a short enough write delay not to be noticed.


----


Photoshop isn't really an option, even with batch processing it's still limited in what it can do. Also I'd have to start up photoshop, copy the images over from the unix system, run the batch, then move them back to the unix system. I can type one command on my unix box, like "exposure_hold -inframe 4647 -outframe 5080 -frames 15 -fade_exponential 2", and everything will be done, including renaming all the frames that come after, as several frames are added to the sequence. Getting windows to rename thousands of files is a real PITA. You aren't thinking or really existing unless you're willing to risk even your own sanity in the judgment of your existence.

Green peppers, lime pickle and whole-grain mustard = best sandwich filling.

*HyperLightBRONZE Member
old hand
1,174 posts
Location: Great Malvern [UK]


Posted:
Written by: Gal koh pan gan

very nice effect but I'm more amazed from the poi. What is that? Home made? How? Where? when? what? Anything...






Those are my HyperLights.. Mark 1 prototypes, so very firmly homemade (for the moment). If you're coming to Falmouth, I'm bringing them along, so you (and anyone else for that matter) are welcome to have a spin smile



@Polarity: You could always do a little interpolation between the frames which are black eek Cake or Death?

pineapple peteSILVER Member
water based
5,125 posts
Location: melbourne, Australia


Posted:
i think im in love with that effect ubblove

i just watched that video *again* for about 20 times in a row.

*drool* "you know there are no trophys for doing silly things in real life yeah pete?" said ant "you wont get a 'listened to ride of the valkyries all the way to vietnam' trophy"

*proud owner of the very cute fire_spinning_angel, birgit and neon shaolin*

flidBRONZE Member
Carpal \'Tunnel
3,136 posts
Location: Warwickshire, United Kingdom


Posted:
Written by: Polarity

copy the images over from the unix system, run the batch, then move them back to the unix system




Samba?

Written by: Polarity

Getting windows to rename thousands of files is a real PITA




That's what the windows port of perl is for

-sandy-BRONZE Member
old hand
716 posts
Location: Bristol, United Kingdom


Posted:
Written by: bender


does after effects natively support photoshop filters?




not really but there are plenty of plug ins available that do basically the same thing.
There is quite a nice one for this sort of thing called T_trail from tinderbox but it costs 300 to buy as part of one of their plug in packs.
You used to be able to download the demo and then find a crack for it but i dont know if they still let you. "Don't do it naked!"

Gal koh pan gannewbie
10 posts

Posted:
Must say: that's the most astonishing, amazing....poi I ever seen. I was thinking for a long while to make somehow a lighted poi without a fire but I guess I'm too lazy. I would love to spin with them but love more to see someone else.

*HyperLightBRONZE Member
old hand
1,174 posts
Location: Great Malvern [UK]


Posted:
That's the only problem I have with my poi - they look much better when you're watching someone else spin them smile Cake or Death?

Pixel74BRONZE Member
newbie
17 posts
Location: Vsters, Sweden


Posted:
There are vid cams that you can change the exposure value on if nothing else. Most of the cams that I have seen have this function...