need help on an effect

C

chris grieder

Well-known member
hey everyone, im going to be doing a little short film soon, in all the shots, the person will be walking around regular speed, but all around him is a timelapse of people. the only way i know how to do this is rotoscoping out the person in after effects, which takes alot of time. does anyone know of an easier way to do this? i have not seen the movie garden state, but i heard this effect is in there too.
 
i thaught about that too, but for some of the shots, hes going to be sitting on a bench at the mall, and i dont think i could green screen that inbecuase he'll be sitting. plus i dont have a green screen
 
Greenscreens are cheap, just go get some fabric. For the mall you can keyframe for everything else greenscreen.

You asked for the easiest way, this is the easiest and cheapest way if you don't want to keyframe everything IE: rotoscoping.
 
For the siting ones, just have him hold very still. And not having a greenscreen is a terrible reason to decide to rotoscope (how much is your time worth, cause with good roto it will take you weeks of work). Basically I think you need to break down each shot and figure out the best way to takle each individual one. If your character is still, then posing in the middle of a time lapse shot works great. If he needs to move at normal speed, greenscreen is your first choice... roto is a distant second. NEVER rotoscope except when you absolutly have to.
 
alright thanks guys, also, i was just wondering, does anybody know how you can add movement to a timelapse (dolly, pan, etc.) i have seen it done before, and im not sure how to do it . i have heard they use motorized heads for the tripods, and program it to move at a constant slow speed. does anyone know any other techniques? thanks.
 
Motorized tripod heads do the trick. Also, if he doesnt intereact with the other people, you could just mask him in.
 
Nik Nerburn said:
Motorized tripod heads do the trick. Also, if he doesnt intereact with the other people, you could just mask him in.
Click to expand...

how do you do that? do you have to mask every frame? im not the best with after effects i only know a couple things
 
I'm doing some extensive roto work right now and here are some helpful tips if you plan to go down that path.

1. Use multiple masks and keep each mask's vertex's under 12. The fewer the better. I am roto'ing a person walking toward the camera and I had 6 masks and it still didn't work right, I'll probably up that number to 12 or so.

2. Keep preserve vertex count checked on. This keeps you from adding new vertex's to the mask, makes for a smoother matte.

3. Preview often, and remember, sometimes you have to cheat your edges and use ones that may not be true to form.

4. This is my number one rule, don't roto until every other option is exhausted, i.e. color, luma, difference keys, and hi-con mattes.
 
The easiest way (yet the most compromising) is to keep the camera completely still and record two different takes; one with just him in the shot, and one with all the other people in the shot at the faster framerate. The compromising part is that you would want to leave enough empty space around the subject so that you could overlay and crop him in the other frame without interfering with everybody else. That is the simpliest way I've found and you can do everything in camera, with little postproduction work other than matching the frames.
 
Oh, and the effect you refer to in Garden State is simply this:

They undercranked the camera and made the subject (Zach Braff) sit completely still while everybody moved around him. This made it look like everything was going completely fast while he remained completely still.

But also, this was recorded as a still frame. I think you are going to have trouble trying to find an easy way to get this effect while your subject is walking, especially if it's all over the frame.
 
that would just be too simple...wouldn't it?

that would just be too simple...wouldn't it?

oops!
 
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that would be too easy....wouldn't it?

that would be too easy....wouldn't it?

TheYankee said:
Greenscreens are cheap, just go get some fabric. For the mall you can keyframe for everything else greenscreen.

You asked for the easiest way, this is the easiest and cheapest way if you don't want to keyframe everything IE: rotoscoping.
Click to expand...
You should know that greenscreen extraction isn't as easy as simply keying out the green. Lighting is most essential aspect to pay attention to. This means even with a shot,that uses naturally lighting, you have to be very aware of where your shadows are and so on. But that's not what makes lighting for greenscreen such a crucial point. Many people think they can just hang a greenscreen behind the subject and record it. WRONG! To get a good extraction when you key you must learn the tools. Remember lots of people do only this all day for a living. Just like you film movies all day for a living. You wouldn't expect a novice to come in and think they can do everything you do. The same goes here. If you really want a good effect find a VFX guy to do it for you. If you are not interested in having help, and really want to make this shot in computer by yourself. You need to do a little more than purchasing a greenscreen.

Yes, anyone can go to a local drug store and purchase a green or blue neon card and make a poor mans greenscreen. But something like this will be evident in your final piece if you do. I mean this in the nicest way possible. You will have a bad extraction and blue or green will still be evident. It will be so obvious.
Plus it will look like a lot of blue/green artifacting around your subject. The poor mans greenscreen is only good maybe for product shots. Then who cares because of course it will only cost you a $1 at Rite Aid or Walgreens.

Investing in good material is key and it will cost a more than a dollar. Not too much but more. If you choose fabric instead of paint there are certain ways you have to hang the fabric. Pay attention when lighting in greenscreen to placement of light in your original footage. This is important. Really important. Lighting is sooooooooo important when dealing with this stuff. IMPORTANT!

Now for computer extracting the greenscreen you have to know your tools. And no it doesn't mean go to color key in After Effects and remove the green as many people think. It just isn't that simple. If it was, why would these VFX guys get paid big bucks to work long hours on films. No, if you want to do this yourself in computer, you have to make mattes to make sure you get a clean extraction. My advice to you would be to study a few tutorials before just jumping in. Learn first shoot later. Here is a website that can help you because it has links to tutorials.

http://www.vfxtalk.com/forum/forumdisplay.php?f=46

If you are overwhelmed by these tutorials it is my suggestion to you that you find a friend on the website, I gave link to, and ask to help with your project. You will be surprised at how excited these guys get. Not all of them can shoot video good like us video guys or girls, and would love to have an opportunity to work with professionally shot video. It will improve their reel and yours too. I know this for a fact. Just post in the Job section that you need help.

two other sites where you might be able to find some help are:

www.3dbuzz.com
www.mattepainting.com

Good luck!
I don't mean to say you can't do it, but it might be much better if you had this clue.
 
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aravance said:
The easiest way (yet the most compromising) is to keep the camera completely still and record two different takes; one with just him in the shot, and one with all the other people in the shot at the faster framerate. The compromising part is that you would want to leave enough empty space around the subject so that you could overlay and crop him in the other frame without interfering with everybody else. That is the simpliest way I've found and you can do everything in camera, with little postproduction work other than matching the frames.
Click to expand...

Actually you would need to record at least three different plates (takes) to set up this shot successfully. It's called a Difference Matte. You need to film the street completely empty of people. Make sure you get a good amount of footage of this, most importatnt part. Next, you shoot with the people in the shot, then with your actor in the shot. The camera cannot move and nothing in the shot can change except for the people. Of course, make sure it is lit well and get a few takes.

Next, you'll bring into a comp package (like AE) and you'll use a difference key to matte everything against your clean plate (the one with no people or actor). What this will do is compare pixel for pixel and remove all the ones that are the same. This way you are left with only the people walking, and only the actor on two different layers. You can then speed up and slow down as you wish, and you have your street background plate on a different layer. Complete control over the shot. Take your time pulling the keys, and you might have to do several passes, but it's much easier (and more common) than pulling a chroma key.

Don't forget, lighting is key!
 
For the dolly move you can build a small dolly, attach a nut to the dolly, attach a threaded rod to the rails (looks like a 4 foot bolt) thread the nut through the rod and you have tiny incremental moves just by turning the rod I turn for every shot.
 
seejay1031 said:
For the dolly move you can build a small dolly, attach a nut to the dolly, attach a threaded rod to the rails (looks like a 4 foot bolt) thread the nut through the rod and you have tiny incremental moves just by turning the rod I turn for every shot.
Click to expand...

If you're going to try to shoot a difference matte, then you would have to 100% precise with this technique. It would probably mess up your chances of pulling a nice clean key, and this is why motion control is so important (and expensive).

If you want to do a dolly move I would do it via camera projection. Slice up your image, project it on some 3D geometry and then do the dolly move that way.
 
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