Looking for Keying help

[scrimski]

Any chance to use another, faster mirror?
It will take around an hour to download and was canceled in the first two download attempts.

[C4DS]

I downloaded the file in seconds, don't know why you have problems. I haven't looked into uploading it elsewhere. Have any suggestions ?

[Polish]

Strange, worked fine for me - Perhaps you could try mediafire.com as an alternative though?
What didn't work for me however, was the .avi source file. I'm on a Mac here, so I guess it's a windows codec I'm missing. Is it possible for you to recompress using animation or another lossless codec in quicktime format and re-upload?
Cheers,
Adam

[C4DS]

Sorry about the AVI format. Didn't think about compatibility issues. The footage were all captured in AVI format, so I just did cut the footage into AVI shots as well.
I tried to render out the sample shot into QuickTime but I don't know which codec and settings should be used to obtain a comparable quality. I tried Animation, Sorenson3, AppleNone, AppleDV PAL.
Some of these codec deliver interlaced results, and I don't see where to set it to render out as de-interlaced. The AppleDV renders blurry results compared to the source file.
And no-compression results into a 60MB file.
I am currently out of ideas to provide a QT file which represents the same quality as the original AVI file.

OK, finally found how to export a QT with deinterlaced settings.
But still, the result looks different from the source image. I'll do some more experimenting, using the QT as source for the keying process and post more later ...

[Polish]

C4DS,
What might actually be easier than faffing with QuickTime codecs would be to export the comp as an image sequence instead? At least us mac users could then suggest some solutions without the hassle for you.
Cheers,
Adam

[beenyweenies]

I didn't watch the clip, but don't need to. Generally speaking, the same three basic issues plague all DV compositing situations, and they are:

1. Poorly lit greenscreen - All the keying skill in the world will not make up for this. If your greenscreen is not properly lit, you have little choice but to use cranked up values in the keyer to get any kind of result. As you've seen, this leads to poor results, especially in your edges.

2. DV footage - DV footage is poor in color information (it only records one color sample for every four brightness samples). This makes it a poor choice for keying, which relies heavily on having clean, rich color channels. A good key CAN be pulled with DV, but you absolutely must have a well lit greenscreen or you are in for some late nights pulling your hair out.

3. One size fits all - Many people who haven't done a lot of keying work try to apply Keylight directly to their clip and pull one key that works for the entire actor/subject. With expertly lit footage shot on HD 4:4:4 or film, this can work. But for anything less, you really must get used to the idea of applying a different key with tailored settings to each different "specialty" region of your actor/subject. For example, the Keylight settings that work well for your actor's pants will not necessarily work so great for their hair. You need a separate key for each.


That said, here's a few suggestions that may help your situation:

Lighting the backdrop - Even lighting with a reasonably high brightness value across the entire backdrop is crucial to a good key. The best way to achieve this is to use flourescent light fixtures (NOT the kind you get at a hardware store, I mean video/film grade lights), or to use bounced light from powerful sources. If you don't have access to several 600watt lights and even a 1,000watt or two, then you should consider renting them from a photo/video supply store for your next shoot. If you don't have the budget to properly light your shots, then you are doomed to battle your keys forever more.

Fighting DV - there are a few techniques to clean up DV for greenscreen. Create an adjustment layer above your footage, and put it in the "Color" transfer mode. Apply the Median effect to it and leave it at its default value. Precompose these two layers together and apply your key to this precomp, rather than the footage itself. The Median effect does a really good job of removing DV artifacting, and will give you cleaner edges. For more tips on working with DV footage, you should go on over to Creative Cow and check out the hundreds of tutorials available. Also, make sure to draw a mask around your subject that removes as much of the greenscreen as possible before keying. This way, the keyer is only asked to remove the green from right around the actor and not the edges of the frame where shadows etc. may lurk. A better technique for this can be found at Creative Cow by searching their tutorials for "super tight junk mattes."

One size doesn't fit all - You really need to consider breaking your footage up into as many separate chunks as needed to optimize your key. If your subject is an actor with hair, you will probably AT LEAST need a separate key for the actor's head. To do this, draw a mask around your actor's head, leaving a good amount of room around it. If your actor moves around a lot, you will need to animate the mask to follow him/her. Duplicate the footage. Open the mask properties for the duplicate clip and tick off the "Invert" box. Now you have a layer with just the head and one with everything else. You should do this for any area that might require its own key. Once you have all your layers, precompose each into it own comp, add the adjustment layer/Median (see above) within each comp and pull all of these comps into one Master composition. Key each comp separately using the settings needed to get a decent result.


Sound like a lot of work? Well, it IS a lot of work to get professional results. The techniques used above are commonly used in visual effects/feature film productions where a substandard result is not acceptable. Greenscreen compositing somehow got a reputation for being the poor man's special effect, but the simple truth is it requires a lot of preparation, at least SOME budget for lights etc. and attention to detail at every step of the process. Every time you miss the quality mark (lighting on backdrop, quality of footage shot, compressed footage etc.) you are increasing the odds that your final product will look fake, cheap and laughable. Quality is king when it comes to greenscreen compositing!!!

[C4DS]

@Polish
The image sequence results in a ZIP file of 33MB, compared to the original DV footage of 6MB.
I am not sure if many would want to download that amount of data.
But I'll upload a zipped file with the 50 frames at:

www.dewensput.be/support/Frames.zip (http://www.dewensput.be/support/Frames.zip) (33MB) (uploaded)

@beenyweenies
Thanks for the information. I already knew some of the DV problems, and wasn't expecting to be able to get a perfect result. But I have seen some DV keying resulting in much better output than mine and hoped to get tips on how to improve my workflow.
However, there are many things you say that I didn't even think about (i.e. using different keys for different parts of an actor). These things may sound obvious to experienced users, and those are welcome hints.

I am already using a mask to limit the keying engine, as for your "Fighting DV" paragraph with the adjustment layer and median effect. I'll have to re-read it a few more time to get what you mean. But again, a very welcome suggestion.

[beenyweenies]

...as for your "Fighting DV" paragraph with the adjustment layer and median effect. I'll have to re-read it a few more time to get what you mean.


An old technique for fixing DV for greenscreen was to just blur the blue/green color channels by 2 pixels, which smoothed out the artifacting just enough to improve the keyed edges, but it does tend to soften the footage. If you don't know what I mean by artifacting, set your comp viewer window to only show the blue channel, which will reveal heavy blockiness and artifacts.

Rather than using the above tactic of blurring, the Median effect does almost the same thing but preserves the footage much better. For this trick to work properly, it needs to be applied to an adjustment layer above the footage, and the adjustment layer needs to be put in the "Color" transfer mode. Each layer has a transfer mode drop-down box, which controls how it overlays the footage beneath it. By precomposing these two layers (footage and adjustment layer) together, you can apply the key to this new precomp. This is necessary because the keyer will not respect effects applied to the footage from an adjustment layer, but once you precomp them the keyer considers both layers (footage and adjustment layer) to be one piece of footage.

If you're still confused, try applying the effect in the steps outlined above and it should make more sense. Or, just let us know what you're not understanding and we can do our best to help.

[Mylenium]

An old technique for fixing DV for greenscreen was to just blur the blue/green color channels by 2 pixels, which smoothed out the artifacting just enough to improve the keyed edges, but it does tend to soften the footage. If you don't know what I mean by artifacting, set your comp viewer window to only show the blue channel, which will reveal heavy blockiness and artifacts.

Rather than using the above tactic of blurring, the Median effect does almost the same thing but preserves the footage much better. ...

To make things even more confusing, you could also get Revision FX' SmoothKit, which does the whole thing adaptively.

Mylenium

[explorer-pl]

Hi

I'm going to download the footage now. For the furute reference, you might try using my hotline when you encounter problems and need assistance.

Here are the details:
http://maltaannon.com/maltaannons-hotline/

Cheers

[coldside-digital]

Hey I had a play around with the footage you supplied. I was able to get satisfactory results using tight garbage mattes, multiple masks for different sections of the footage, such as the hand, body and head.

Included in the zip file is the AE project, which has the keyframed masks, and a video showing the result. The only problem is that I used DVMatte Pro for the keying, which is made exclusivly for keying dv footage. You will have to substitute in your own keying algorithims using keylight or whatever other keying plugin you choose, unless you own DVMatte. If you still can't get satisfactory results, and you like my key result, let me know and i'll render out the alpha channel for just the greenscreen footage for you to use, unless of course, the shot is longer than what you've supplied. If thats the case, ill apply what i have to the full lenght footage, and then render out the alpha channel.

Heres the ZIP file:

http://www.sendspace.com/file/7h8fr6 (9mb)

Hope that helps.

ColdSide Digital

[C4DS]

@coldside-digital
I watched your result and was really impressed, looking forward to see how you achieved this.
I downloaded your file, but I am only using AE version 7 which couldn't open it.
The footage is indeed only a part of the complete shot. And I have several shots that have this same keying problem.
I hope to learn from your file how to do the actual thight garbage mattes and masks.
Is there a possibility in CS3 to export a version 7 file ?

Your result is exactly what I was looking for.
Thanks again for the time you spent on this.

[coldside-digital]

In the next few days, I'll put together a basic video tutorial and possibly a written tutorial, if it would help you. I've been looking for a way to open a CS3 project in 7 but haven't found anything helpful so far. Ill try and see if I can copy the mask shapes and settings or something. Maybe if you downloaded the CS3 trial and opened it up in there, you could get a better idead, and possibly copy the masks.

So yeah I'll make those tutorials and hope it helps. I am willing to work on the shots for free if it would help you at all. I need to get some more practice and I dont have any footage to work on at the moment. I could even do it in 7 Pro if that would help.

Just let me know,

ColdSide Digital

[C4DS]

Thanks.
Very generous of you to propose to work on the shots for free.
I am sure I'll learn a ton from your tutorial, having seen the resulting key you managed to pull from the footage.
I'd like to learn how to do it in a good way.
In return, I can provide you with some greenscreen footage (DV PAL format is also used in Australia, I think).

The project includes a massive 208 shots. In some of the shots there are 3 actors to be composited (each filmed separately, due to different character sizes in the movie).
It is not my intention to let others have to struggle with all the keying, but I'd like to learn from others.
I can give you some of the more "challenging" shots for you to practice on ... and we can compare whos result looks best ;-)

Thanks again.

[coldside-digital]

Yeah, the PAL format is used in Australia.

With the shots containing the three seperate actors, are they shot with the correct scale, or will it be changed digitally? If so, i'll let you decide what size will suit best, then you can just give me the information on how much you scaled it down/up.

Do you have a deadline for the project? Oh and I like a challenge, so if i can help out, I'd like that :buttrock: lol

If possible, definitley upload some more challenging shots, and ill try my hand at them, and document the process for you.

Oh and if i was to work on some of the final shots on the film, the only thing I ask for is a credit :)

Do you have msn? or gmail?

MSN- murder_at_the_masquerade@hotmail.com
GMAIL- ColdSideDigital.Admin@gmail.com

ColdSide Digital

[C4DS]

A few answers to provide public information.
The project has no official deadline, the target deadline is when the movie is done.
The actors are filmed separatly without taking scale into account, I wanted to get the largest possible image of everyone to start with. Scaling is done in post.

I don't have gmail, but have an hotmail address, I'll contact you shortly.
I'll see to collect some challenging footage for you to practice on.
The least I can do is give you credit for the work you deliver.

thanks again.

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