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Green Screen Dancing Edge Pixels (After Effects CS6)

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Matt Dodds
Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 4:15:54 pm

Hello,

I am having some dancing pixels issues. I am using this tutorial for chroma keying/keylighting my green screen footage:



and it works for the most part, but when I put a background to it, it is showing some dancing edge pixels around her head:





I have researched and looked online to eliminate this problem and haven't found any solutions. I don't have that great of a green screen and my 60D doesn't pick up the light I want, even using 3 lights to record with (I work at a vet, doing video, so I am limited to spaces to record footage). I am using CS6, so Key Cleaner isn't an option for me and I don't have the funds for a plug-in, since I am wanting to do video bios with green screens in the future!

Any advice or help is very appreciative! Thanks!


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Dave LaRonde
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 4:41:29 pm

You're obviously limited in two key areas vital to pulling off a good key: adequate lighting and depth to separate the subject from the key background. "Not that great of a green screen" implies that it's small, a common mistake.

I don't know your location, but you MIGHT be able to shoot outdoors, allowing you to use Mr. Sun for key, a cheaply-made reflector for fill, and angling the green screen so it's in shadow... which would go a long way to a better key.

Just keep the audio quality in mind -- you don't want traffic sounds when you're creating an interior shot.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 4:52:43 pm


This is an image of my green screen set up. When I meant not a great green screen, I meant cheap and wrinkly, not small. It came with my lighting set up I bought.

I am currently not able to record outside, since it is still cold and will be snowing soon! Inside is my only option so far!

Thanks!


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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 5:21:44 pm

If you can, get it stretched on some sort of frame. Also, get as much distance as you can from screen & subject.


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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 5:18:03 pm

Are you using the Keylight keyer that comes with CS6? There's a Screen Shrink/Grow control that taking it into the neg direction should help. A tiny bit (like -.7 to -1.5) of that plus a touch of Screen Softness should help.

In the future, try adding a bit of back light on the subject. Doesn't have to be much; just noticeable to the eye. That will often clean up the subject edges from green spill.

Above all else, use an external mic & get it much closer to the subject, just out of frame. More people will notice that over any matte issues.


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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 6:30:31 pm

Adding to Mark's comments: when shooting blondes try and go for Bluescreen - color keys are really just fancy difference mattes and there isn't a lot of "difference between" yellow hair and green screens.



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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 8:30:47 pm

So, that is the reason why I am getting dancing pixels. That does make a lot of sense then. I will try to get a blue screen and get more distance from the screen, than I was before. I think that this footage isn't usable then?!


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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 21, 2018 at 6:22:34 am

[Matt Dodds] "So, that is the reason why I am getting dancing pixels. That does make a lot of sense then. I will try to get a blue screen and get more distance from the screen, than I was before. I think that this footage isn't usable then?!"

Replied to this earlier but it vanished into the ozone. Anyway, you might want to take a look at this short making of that shows what can be done on a shoestring budget yet paying attention to the basics:



VideoCopilot has a bunch of good tutorials as well.

You might research doing multiple keying passes but if you've a wrinkled, moving green backing, you're fighting an uphill battle.


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 8:36:39 pm

I am using the Keylight 1.2 keyer. I have been using the Screen Shrink and putting it at -2 and the Softness at 2. Neither of these were of any help!

I did put 2 lights on the background to light it up, but I only have fluorescent light bulbs, but I plan to get some LED lights.

I do use a lavalier mic, with a zoom recorder. The lav was in her scarf! I did noise cancel the sound, so that shouldn't be an issue!


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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 9:10:55 pm

That screen is probably a little too emerald to be used as a true green screen (real ones are a little more neon/glow-in-the-dark kind of green)
But there's always a way. What you might be seeing is the compression on the footage. We had some HD footage in the early days of HD on blue screen whos edge was very very ratty. That was pure codec problems.
What codec was used to capture and have to got that original footage or are you working with a compressed version of the original?

We had a client send us some bluescreen footage - the screen was a made of demin - sort blue I guess - but guess what the talent was wearing? That's the only screen we've never been able to pull a decent matte from in 38 years of work.

Next time try getting some green kino flos or similar to light the screen with. The lights you use to light the talent will wash out the screen soon enough so if you can light the screen with the same color as it already is the keys are stellar.
And don't be afraid of green spill - its actually important because it lets you put some of the new background's color in as though it's whats being spilled on the actor.

Can you post a little of the running footage and we can give it a whirl? Doing a comp on a still won't reveal the dancing edge problem.



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 10:32:44 pm

I finally had a sec to pull a key off the still you sent. Is the screen being buffeted by a fan by any chance? I think the dancing edges are the creases in the screen showing up and perhaps fluttering. You may need to use the blur feature in Keylight to pre blur the screen to diminish those.
Or you can pull two keys one for the dark greens and one for light. Or pull two keys one for the body of the person (clamp the heck out of it) and then do a roto matte (very loose) around her head, make a thick fuzzy line out of that mask and then use that as a mask. (basically a halo of the edge of her hair). Combine that with a thin green key that lets some of the screen show through. Then you can have a much less dense matte and you can screen that element in over top of the main chunky matte of her. Because its blonde hair it screens well and lets you keep all those split ends even though the matte isn't great/solid.



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 20, 2018 at 10:37:44 pm

Like this (the image uploader failed so I had to inlcude it as a file)
12272_edgematte.jpg.zip



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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 21, 2018 at 9:38:38 pm

There is no fan at all. It is just her with one light on her and 2 lights lighting up the green screen, since my 60D doesn't pick up much light, I wanted to have the green screen have the most light possible, to make the chroma keying easier, which it hasn't! I have been trying to use some of the blur feature, but to no avail.

"Or you can pull two keys one for the dark greens and one for light. Or pull two keys one for the body of the person (clamp the heck out of it) and then do a roto matte (very loose) around her head, make a thick fuzzy line out of that mask and then use that as a mask. (basically a halo of the edge of her hair). Combine that with a thin green key that lets some of the screen show through. Then you can have a much less dense matte and you can screen that element in over top of the main chunky matte of her. Because its blonde hair it screens well and lets you keep all those split ends even though the matte isn't great/solid."

That would work, but it is mainly her hair that is doing it. I also did it with mine (did a test recording) and it was also doing the dancing edge pixel around my head and clothes. I am just confused at what I am doing wrong!


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 21, 2018 at 9:32:49 pm

I do believe the codec I am running is H.264. And for compression, I am not doing anything myself. I am uploading it from the SD card to a folder, then to After Effects, so AE might be doing the compression, if any at all, but I am not manually!

Yes, here is the beginning bit of it. I added the clapboard part to it, since it doesn't key out the clapboard correctly as well!

12279_shortgreenscreen.mp4.zip

Thanks!


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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 21, 2018 at 10:30:25 pm

While I play with this....
Normally you want as uncompressed as possible to pull keys from. And a 4000kb/s H264 is a long way from that. You have lost so much chroma in the compression and there is so much artificial edge reconstruction going on in the codec that its just making your job that much harder. Keep in mind HD uncompressed (at 8bit) is about 186mb per second; where this clip is 6 seconds long and only 3.5 mb so theres a huge amount of data that's missing. (and normally we're working with either a RAW format or a 10bit color file or even better a 16 or 32 bit EXR file - these have so much color space you can hear an echo!)
So I think the combination of the creases in the fabric and the low quality of the codec bit rate is whats doing you in.
The screen doesn't have to be moving to cause issues with the creases - if you look at compressed video really really really close you can watch two objects that overlap act like lava lamp blobs - as the front object moves, its edge seems to coalesce with details in the background, changing the shape of the edge. This also has to with how lenses and irises work (ok, what's the plural of iris? iri?)
Let me try and pull a key and i'll post the results. I'll limit the test to only effects in AE.



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 21, 2018 at 11:21:23 pm

So here's a couple of things:
This is a green screen image with H264 compression (and pretty mightily compressed at that) and you can see everything is sharper but more than that, the visible blocks that make up the H264 compression are away from the hairline, out in the green area where subtle shades have to be decided on. All blocks change every keyframe but with the obvious ones out in the green you won't see the key dance every 15 frames or so at the hairline.



In your footage there is no where near the clarity of detail and there are all these little smudges where the codec (or the camera) has tried to invent what it's seen or average a bunch of data into a few blocks. The more noisy a shot is (by noise I mean lots of different textures and colors and details - in other words the wrinkles in the fabric) the higher the Mb/s it needs to make sure all of those details come out sharp and at 3.5 mb/s sec its just not enough, given the content of this shot. Any codec is going to start to sacrifice things (usually color first) in order to keep details it finds important. One of my clients loves h264 because at a low through put rate all her wrinkles disappear.



If you zoom in on your footage to this level and step through it frame by frame (no key or effects) you can see the edge of the hairline boiling and little areas of distortion going on where chunks of hair literally move over 16 pixels for a few frames and then move back or sections get averaged to keep the bandwidth. This may be function of the camera or the codec, I'm not sure, but this is also going on at the edge of the hair so you are keying a moving target. It's almost has a shower glass effect.
Still playing but I thought I would share.



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 21, 2018 at 11:23:57 pm

I think my jegs got a little crushed in the upload (the irony is not lost on me) so the details i'm pointing out aren't really that evident - let me know if you want the originals



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 12:40:40 am

Try this one on for size. This uses the clips you uploaded (the original footage I've squished the head out of to get an incorrect but clean background plate so the lighting is right) and the last raw footage clip.
I think it boils less than the one you showed us and certainly doesn't suffer from the edge blockys. It does crush her hair a bit more but another edge hair layer compensates and brings some of the wisps back in. This layer actually looks better on top but it does change the color of her hair a bit. If you can live with that difference in color (if you didn't see the original you wouldn't realize) it brings more wisps back in when placed above the footage.
I've added some noise to the BG to match the noisy green screen footage.
Let me know of you need it saved back before AE 2018.

If its not good enough it may give you some ideas that you could tweak yourself.


12281_greenscreenheadcomp.aep.zip



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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 8:05:20 pm

[Steve] "Try this one on for size. This uses the clips you uploaded (the original footage I've squished the head out of to get an incorrect but clean background plate so the lighting is right) and the last raw footage clip.
I think it boils less than the one you showed us and certainly doesn't suffer from the edge blockys. It does crush her hair a bit more but another edge hair layer compensates and brings some of the wisps back in. This layer actually looks better on top but it does change the color of her hair a bit. If you can live with that difference in color (if you didn't see the original you wouldn't realize) it brings more wisps back in when placed above the footage.
I've added some noise to the BG to match the noisy green screen footage.
Let me know of you need it saved back before AE 2018.

If its not good enough it may give you some ideas that you could tweak yourself."


I would need it at the CS6 format please. I am not able to use it at 2018.

Since this is for a professional video bio, I need to make sure I get enough hair in there.

Thank you so much for your help. I am assuming it comes back to lighting then. Since I do not get enough light at Shutter Speed 1/30, F-stop 3.5, and ISO 400 (that low, since I get a lot of grainy noise if it is any higher), what would you suggest for an less expensive light setup? I was thinking LED lights, but that might not work out for a green screen.


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 7:56:07 pm

"This is a green screen image with H264 compression (and pretty mightily compressed at that) and you can see everything is sharper but more than that, the visible blocks that make up the H264 compression are away from the hairline, out in the green area where subtle shades have to be decided on. All blocks change every keyframe but with the obvious ones out in the green you won't see the key dance every 15 frames or so at the hairline."

What codec would be better to use? In school, we were taught H.264 due to it having a higher HD quality, but it's not helping me here. Also, it looks like your green screen is lighter. Is there a specific hue that a green screen should be normally, or does it really matter?



"In your footage there is no where near the clarity of detail and there are all these little smudges where the codec (or the camera) has tried to invent what it's seen or average a bunch of data into a few blocks. The more noisy a shot is (by noise I mean lots of different textures and colors and details - in other words the wrinkles in the fabric) the higher the Mb/s it needs to make sure all of those details come out sharp and at 3.5 mb/s sec its just not enough, given the content of this shot. Any codec is going to start to sacrifice things (usually color first) in order to keep details it finds important. One of my clients loves h264 because at a low through put rate all her wrinkles disappear."

Would better lighting make a difference or is it all just a codec thing? Is there a green screen/blue screen that is better to use? I am wondering if there is a fabric that does better with wrinkling, since I am not able to iron it out at site! I have been trying to use the Selective Color effect to help lighten the greens up, to get rid of the wrinkles as well, but it hasn't been working!



"If you zoom in on your footage to this level and step through it frame by frame (no key or effects) you can see the edge of the hairline boiling and little areas of distortion going on where chunks of hair literally move over 16 pixels for a few frames and then move back or sections get averaged to keep the bandwidth. This may be function of the camera or the codec, I'm not sure, but this is also going on at the edge of the hair so you are keying a moving target. It's almost has a shower glass effect."

Is there a way to alleviate this problem, if any?


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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 9:00:19 pm

[Matt Dodds] ""If you zoom in on your footage to this level and step through it frame by frame (no key or effects) you can see the edge of the hairline boiling and little areas of distortion going on where chunks of hair literally move over 16 pixels for a few frames and then move back or sections get averaged to keep the bandwidth. This may be function of the camera or the codec, I'm not sure, but this is also going on at the edge of the hair so you are keying a moving target. It's almost has a shower glass effect."

Is there a way to alleviate this problem, if any?"


Quite simple: As we've mentioned, just get a bit better exposure on your subject (add some backlight) and more uniform process screen exposure. From the sample you posted, it uses a chroma subsampling of 4:2:0. Common, looks fine in most cases, but doesn't leave much wiggle room when doing keying work.

To fix this shot: No quick/easy fix really. Least painful is to reshoot if possible after you get your set-up dialed in and those ARE easy fixes.


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 7:41:07 pm

This makes a lot of sense. I am not able to record in RAW, since there is no option for that in my 60D. I did research it and it looks like most all of Canon DSLRs, without Magic Lantern, uses H.264 or something similar to that.


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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 2:07:32 am

[Matt Dodds] "I do believe the codec I am running is H.264. And for compression, I am not doing anything myself. I am uploading it from the SD card to a folder, then to After Effects, so AE might be doing the compression, if any at all, but I am not manually!"

Hey Matt,

Looks like Steve is giving you some assistance. I can't really as I'm "archaically" still using CS6.

Here's tiny utility though you might want to check out. It installs as a windows Explorer Right Mouse Click menu item when you've any sort of media file selected. It'll give you a LOT of info on the files make-up such as codec, frame rate, bit rate, etc. Very worthwhile having to diagnose with.

https://mediaarea.net/en/MediaInfo


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 8:11:57 pm

[Mark]"I can't really as I'm "archaically" still using CS6.

Here's tiny utility though you might want to check out. It installs as a windows Explorer Right Mouse Click menu item when you've any sort of media file selected. It'll give you a LOT of info on the files make-up such as codec, frame rate, bit rate, etc. Very worthwhile having to diagnose with."


I completely understand. While I was in school, we AE CS6 for my Digital Effects class, but after that class, they changed it to that current years CC, so I just used CS6 due to funds! For video editing, we used Avid Media Composer, so I have been on a different level on everything or a little behind when it comes to programs!

I just downloaded it and I will use it for now on. We never really learned codecs, we more focused on camera angles, editing, and ISO/F-stop/Shutter Speed!


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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 8:28:10 pm

Hey Matt,
It looks like the forum didn't update properly so I missed your long post with my comments in quotes - let me answer those shortly.



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 22, 2018 at 10:13:47 pm

Here's a lengthy response to your question where you quoted my answers:

I think all the issues are due to the codec and the camera.

Some cameras just don't produce a clean image. The camera makers can hide a number of sins, including a blocky image, by adding noise and this may have been done on that camera. There's a reason a RED camera is $40k and Arri's go for more than $100k (and that's before lenses and doodads!) and prosumer cameras are only in the $1500 t0 $5k range.
Shoot with the best camera you can (we'll even rent a special camera just on the green screen days while the rest of the production is shot on something else less costly)

When we do green screen we are so picky that we ask for a digital feed out of the camera, live on set- that feed is usually uncompressed, but even if it isn't, its always miles better than what goes to the tape. Very few cameras record uncompressed to tape. 4K files are so massive that you wouldn't get too much footage on a single tape - you would be pining for the good old says when film reels were only ten or twenty minutes long.
That feed goes right to our capture card which is capturing in an "uncompressed" lossless codec in 10 bits. And that goes right to our hard drive array. This way we can also do a test comp on the set to make sure the key is pullable. There is just no comparison between any version of H264 and this kind of file. H264 was made as a final delivery codec and not one for doing effects with. So much of the information you need for effects is long gone on a H264 compress even when its done way up at 40mb/s (twice blue ray). Even Apple's ProRes is way better than H264 for effects work. Do a a little research on what 4:2:2 or 4:4:4 means (and all the other combinations) with regard to color space in codecs and cameras. Its shocking how little color information is needed to convince the human eye they are seeing reality. Keying software is not that easily fooled.

But you can't always get to the set or they don't want to "waste the time" (more on this later). And you don't always want to rent a deck to capture the footage with. So if you can have someone digitize the footage you should ask for a high color space format. Like EXR or ACES or RAW (if you can handle this one) or Cineon. And you will get stills, not movies. Sometimes you can get the camera's proprietary format, like on a RED. What ever it is, get as close to uncompressed as you can with the largest color space (8 bit is just so last year!). But make sure you have have a codec that can read that format. (in this instance codec doesn't mean compression; more so its compatible and readable by AE). We like EXR - AE, Photoshop and most 3D software reads it out of the box, its 16 bit or 32 bit, can hold an alpha and multipass rendering.

The DPX format (and I'll be branded a heretic here by some for saying this) seems to have a different flavor depending on the camera. The big cams that use it (like Arri) use it well but some of the prosumer cams use it too and have mangled it. It can be excellent but it can also be terrible. Ask for a set of test frames. Watch what happens when you play it - view zoomed in at 800%.

As for the ideal color for the screen it really depends on the camera, subject matter and what screen material you can get. If you get a pipe frame for your screen, you can stretch it across the frame to get most of the wrinkles out. There's no point ironing the whole thing because only parts of it are in the shot or its so far back its out of focus. We take a steamer to set for pesky wrinkles that are showing. Under the strain of the frame those wrinkles take one look at the steamer and straighten up right quick. The frame also means you don't have to tack the screen up - just attach the frame to two C stands.

If you light the screen with green gelled lights (barn door those lights so none of that falls on the talent) you can pick your gels to tweak the color of the screen. You have to balance these lights with the ones that light the talent which also fall on the screen. We light the screen first so we can start with that evenly lit. The minimum we shoot for is 20 feet between screen and talent and another 20 feet to the camera. A short lens used in green screen screams "Effects shot!" and never looks real. A good distance from your screen also means the bounced spill light from it will be minimized on your talent's edges - which is the all important keying area.

We get the camera info before hand and then look at the color sensitivity of the CCD (or film stock if you are going that way). Look at where the green color arc peaks or where the green arc is the farthest from the red arc and choose a color for the screen or the gels that gets you closest to that frequency of light. There are color meters out there that can measure this when you look at the screen through them.

But all of that is probably moot on a shoestring budget. That image I sent you is a very nice color of green as a rule of thumb - kind of dayglow lime green. The one you used, while functional, is a little too forest green or emerald green (its got too much blue in it). The idea here is to pick a green that is not "contaminated" by either of the other two primary colors - add some red and the screen is more yellow green, add too much blue and you get your color. You want that screen only showing up in the green record of the file. You can still key with your color, or any color for that matter (ironically the best screen color is red, just not for people) but the closer you can get to the magic color the easier the trickier stuff is - fine hair, veils, glass, water, reflective stuff.

A 20 foot by 20 foot screen (called a "20by" written "20x" in the industry if you are renting) is pretty much the smallest you want. By the time you get the screen back twenty feet from the talent (a minimum you should shoot for) a 20by just barely covers a person head to toe. Renters also have standard frames that fit this size. From there they go 20'x40' and 40x40. And they do go bigger for outdoor landscape masking screens. You can also paint a cyc in a studio. Green screen paint is crazy expensive (because its hitting the magic color) but you can get Home Depot to match the color you want - matte always. Take in a bit of green screen gaffer tape for them to match.

Lighting is important - try and get a smooth and even a lighting pattern across the screen - use a spot meter to measure side to side and up and down and in the center. Again you can key without this step but often you have to pull multiple keys for different sections of the screen.

Codecs - H264 is a miracle and has single handedly made the internet a viable delivery mechanism for movies (in 1991 I said this was something that could never happen because of film resolution and internet bandwidth - but then I'm in good company: Richard Edlund said the same about digitizing film into a computer the year before, and Bill Gates said 640kb was all you would ever need for RAM - the moral? Never say "never", or try your hand at futurecasting). But H264 is not a good effects format for your fx source. Sure its lightweight to send around over the internet but you want every drop of data you can get from the shoot and you don't want the codec fudging the truth just to get the file size down.
Blackmagic Design has an excellent codec that bridges the gap between a lightweight compressed (but noisy) codec like H254 and the near perfect but massive records of a RAW or EXR. And as luck would have it they also make capture cards. You don't need the capture card to work with BMD's format but you do need one to play the format real-time. They also make an excellent and reasonably priced cinema camera (whether they have any in stock is quite another matter)

I know this all sounds like a lot to hoist onto a director because the effects guys are already the thorn in his/her side slowing down principle photography. But getting the details right will make your composites go so much smoother and you will have more latitude when something was done incorrectly, or there is too much motion blur in the footage to pull a key, or the tracking markers aren't showing, or or, or....
Keep in mind too directors are terrified of the effects side of things. So while you are a time delay distraction with all your requirements, they know that it's in their best interest to give you what you need to work with or their post budget will soar.



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 23, 2018 at 12:56:23 am

I went searching for camera footage in H264 and couldn't find any that were compressed as low as what you uploaded (even my gopro has a higher bit rate that this) Are you sure you have camera footage and not someone's recompress?
Take a look at the footage in the link below - its H264 (albeit at 10 times the bit rate of yours) and it keys with one click. Its clean enough for a good key, keeping the whips of hair at the edges.
While you do have issues with wrinkles in the screen there has to be a cleaner record of this footage somewhere. And that would help you immensely.
12287_171003d0172k.mp4.zip



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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 23, 2018 at 1:49:16 am

[Steve Bentley] "While you do have issues with wrinkles in the screen there has to be a cleaner record of this footage somewhere. And that would help you immensely."

Good catch Steve. Here's a report of this footage vs. Matt's using the MediaInfo utility:

Matt's "Bad Greenscreen:
General
Complete name : D:\AE CS6 Projects\From 2018\Misc Sources\12279_shortgreenscreen.mp4
Format : MPEG-4
Codec ID : M4V (M4V /mp42/isom)
File size : 3.63 MiB
Duration : 6 s 590 ms
Overall bit rate mode : Variable
Overall bit rate : 4 626 kb/s
Encoded date : UTC 2018-03-21 21:30:25
Tagged date : UTC 2018-03-21 21:30:25
TIM : 00:00:00:00
TSC : 24000
TSZ : 1001

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Baseline@L4
Format settings : 2 Ref Frames
Format settings, CABAC : No
Format settings, RefFrames : 2 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 6 s 590 ms
Bit rate : 4 455 kb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.090
Stream size : 3.50 MiB (96%)
Language : English
Encoded date : UTC 2018-03-21 21:30:25
Tagged date : UTC 2018-03-21 21:30:25
Color range : Limited

Steves "Good" Greenscreen:
General
Complete name : D:\Ttemp\Toss\12287_171003d0172k.mp4
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (mp42/mp41)
File size : 87.2 MiB
Duration : 22 s 880 ms
Overall bit rate : 32.0 Mb/s
Encoded date : UTC 2018-02-08 16:16:18
Tagged date : UTC 2018-02-08 16:16:19
TIM : 00:15:18:06
TSC : 25
TSZ : 1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4.2
Format settings : CABAC / 2 Ref Frames
Format settings, CABAC : Yes
Format settings, RefFrames : 2 frames
Format settings, GOP : M=4, N=25
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 22 s 880 ms
Bit rate : 32.0 Mb/s
Width : 2 048 pixels
Height : 1 080 pixels
Display aspect ratio : 1.896
Frame rate mode : Constant
Frame rate : 25.000 FPS
Standard : PAL
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.578
Stream size : 87.2 MiB (100%)
Language : English
Encoded date : UTC 2018-02-08 16:16:18
Tagged date : UTC 2018-02-08 16:16:18
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
================================================

So ya, either his got re-encoded OR there's something amiss with the camera settings. Note the Bits/Pixel Frame values. Just nothing there.


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 23, 2018 at 9:33:02 pm

Hey Mark,

I did post my MediaInfo on the footage off my SD card and the bit/frame rate is showing at .925 and not at the .578 of my exported footage from Premiere. I am not sure really how to change the bit/frame rate at the settings. I did look at all the menus, but nothing is showing about that!

Thanks!


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 23, 2018 at 9:34:35 pm

Hey Steve,

Sorry I misread your info, I didn't see the .090. Dang... that is low. Again, I am not sure what I need to do to change that!


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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 23, 2018 at 10:24:06 pm

Not sure either if it's a camera setting. But if it was just that your footage got reencoded somewhere along the line, hopefully you can simply track that down.


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 23, 2018 at 9:30:27 pm

Hey Steve,

In school, we used a Blackmagic camera in our RAW class and it worked out great, I'm just not the best when it comes to RAW footage and color correcting. I don't have a budget when it comes to renting things and we used a 60D in school (our lower classes), so I got that one because it worked well. I was thinking about getting a 80D because I do have people in my state, that are videographers, that suggested that.

This is the info from MediaInfo about the footage from my camera:

Complete name: E:\DCIM\100CANON\MVI_1882.MOV
Format: MPEG-4
Format profile: QuickTime
Codec ID: qt 2007.09 (qt /CAEP)
File size: 364 MiB
Duration: 1 min 4 s
Overall bit rate: 47.5 Mb/s
Encoded date : UTC 2018-03-14 13:50:56
Tagged date : UTC 2018-03-14 13:50:56

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Baseline@L5
Format settings : 1 Ref Frames
Format settings, CABAC : No
Format settings, RefFrames : 1 frame
Format settings, GOP : M=1, N=12
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 1 min 4 s
Bit rate : 46.0 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Original height : 1 088 pixels
Display aspect ratio : 16:9
Original display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.925
Stream size : 352 MiB (97%)
Language : English
Encoded date : UTC 2018-03-14 13:50:56
Tagged date : UTC 2018-03-14 13:50:56
Color range : Full
Color primaries : BT.709
Transfer characteristics : BT.709

I exported the 6 sec clip from Premiere in H.264/DSLR, so that is one reason why it might not be working on your end. It looks like my codec that it is using is AVC, which might be less compression?

The thing is I use all of my own equipment, so I don't rent or borrow anything. I do need to look at the footage zoomed in on my camera, as it always adds grain and it's not flattering.

For the screen, I thought about that, but it is difficult to get them and set them up everytime I shoot, so I normally thumbtack it up, which I understand isn't the best option. I did order a blue-screen, since I did get some advice, outside of this forum, that a blue screen might be a better option, but everything you talked about, it probably wont work with my camera and it's settings.

Where can I get green gelled lights and do you have a good lighting kit? I bought a photography lighting kit with fluorescent light bulbs, so that is my only thing I have. It just sucks that my camera and lens doesn't pick up enough light to do much with it. The next time I record my next veterinarian, I will have them farther away from the green screen, I just know that I will not able to to use the footage I have too much, since the deed is done. I am just happy I recorded the footage without the green screen!

Since I am an one-man team, I am not able to do everything like that by myself, especially with no budget, besides what comes out of my pocket. I liked the dayglow lime green color. Again, I got this green muslin from a photography kit, so it was what came with it. I will try to find a dayglow lime green color muslin for my next shoots.

Again, I am limited on what I can do at the place I work, so I will have to try to find a 20by or 20x.

Lighting has been one of my biggest weaknesses. I want to get some LED lights that I can change from Tungsten to Daylight, as I think that would fit the feel of my work, but I just don't have the best lighting set up. I did try to light the green screen more, since I knew that would be my biggest issue, but it looks like I need way more lights than I have!

We were taught that H.264 was something that was really great, and it is, but not for what I am doing! We even used a 60D and H.264 format and pulled a good key (one of the only times we used green screen work). It can be done, but it's very rare and I understand what you are saying.

What kind of capture card are you thinking/using?

I took a digital effects class in college and it was fun, but something that I never wanted to do full time/as my career, but green screen work sounded fun, but after this experience, I know I have way more to learn about stuff like this and it's nice. Like stated above, I am an one-man team, so I am the director, producer, editor, renderer, and poster, so I do it all. I do get some guidance from my supervisor, as to what I should be recording, but nobody knows about film/video/recording, so that is why I came to this blog. I did research this topic before I came here and learned some stuff, but nothing compared to my dilemma, so I do appreciate your help and with your words of encouragement and guidance, I will try to work it out. My next plans of action is to figure out what codecs I can record in, on my 60D, the distance from the background and the screen/frame, getting a new lime green screen, and maybe getting a better camera body, since that might be some of my issue there (due to not picking up enough light).


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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 23, 2018 at 10:28:50 pm

Is it possible that as you work with premier (or whatever) and AE you are rendering your edit chunks out for use in AE and therefore the footage is being compressed and recompressed and recompressed? Compressing an H264 gets exponentially worse the lower the original bit rate is. And then if you recompress that, well, its starts getting very noisy. If you must render out clips to use in AE use a truly lossless format. Since it's coming from H264 even Quicktime Animation best is lossless and high quality for that kind of process (and its runLengthEncoded so green screen stuff has very low file sizes without loss).
Are you color correcting the files in Premier before they go to AE? You want as raw an original as you can get for the key - every time to color correct you loose information. Try it - take an image in pshop and look at the histogram - now color correct that image, flatten the correction (make it so!) and then look at the histogram again. Instead of a continuous set of curves of the colors you get a spiky skyline - all those gaps are missing data.

H264 can work (as I think that clip I uploaded shows - at a higher bit rate at least) but the idea is to get as good a record as you can of the on-set stuff because something will cause you grief and the cleaner the matte you can pull without any tricks, the more tricks you have left to fix other stuff.
Did the AE file I sent with the key in it not work out well enough?
You could try another keyer - Primatte makes a good one - not sure if there's a demo or the cost. There's the granddaddy of them all - Ultimatte. Sometimes another compositor (Shake, Combustion, Nuke etc) will have their own keyer that will be dialed in just right to pick out details that others miss.
There used to be a pro version of the Keylight keyer too. It could tease out that much more of your edges.

In the end though, the clip you uploaded is really noisy so there will only be so much you can do without by-hand paint repair. When it comes to fixing green screen shots, rotoscoping certain areas is not a dirty word - most of the lord of rings got roto'd even with all their blue and green screen work. And don't forget you don't need a perfectly opaque matte - its ok to have a bit of the white part of the matte (the head) be grey - you can always make a garbage matte that is rough and fills most of that back in and leaves a feathered edge being a little transparent, and being able to see hair wisps at the edges is far better than helmet head.



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 23, 2018 at 10:43:32 pm

Rereading your posts again: at that bit rate out of the camera you should be ten times better than what we saw. Grab a bit of the original camera footage and pull that into AE (ignore your edit list for moment - we just want to see if unadulterated camera originals can key ok.)
I'll bet its the crush coming out of Premier that's killing you.



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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 24, 2018 at 8:25:02 pm

Hey Steve, my work flow is SD card, to file folder, to AE. I don't go to Premiere first, since I don't need it in Premiere, until after I get it done in AE. Would moving it to a file folder be an issue as well? If you want, I can put it on my dropbox or google drive and share the link, that way you have it uncompressed. I only put it in Premiere, to sample a bit of my footage, since my file is over the upload file size on here!

I need to figure out what bit rate my camera does, but I looked at all the menus and nothing was showing me the bit rate. I don't wanna go for Magic Lantern, since I don't wanna break warranty!

I can't get your file to work with my AE, since I have CS6 and cant work with AE CC 2018. If you can send me a CS6 format, that would help better!

I will look into all the keyers you mentioned. I am assuming they all cost. I had to buy Neat Video noise/grain reduction for my school projects, so maybe that might be something worth while!

I am not sure how to rotoscope, so I will research that. I just need to make sure I just have enough light and distance, so that way whatever technique I am able to use, it will make it way easier for me!


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Dave LaRonde
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 24, 2018 at 1:00:18 am

Okay!

Understand that I have Not looked at everything in this thread.

Unlike Steve Bentley, I find that a DARKER green screen background -- with NO wrinkles in it -- cuts down on the noise in the key in Keylight. If you MUST go with a very bright green screen background -- and that's just silly -- you have alternatives. I suspect a reshoot is in orfer.

You MUST learn how to use Keylight. And then you MUST learn how it really works.

The most important thing to learn is that Keylight pulls a good key, and you will discover it in the Status view -- gray on the edges, and white, with tinges of green in the core. Don't be afraid to mask around the subject. Or even to animate a mask.

OKAY. So let's say you have a good-looking key according to the status view. YOU DON'T HAVE TO USE IT AD YOUR FINAL KEY. You can use the keyed layer as a track matte for a duplicated, unkeyed layer. Got light spill? Use Keylight on the unkeyed layer to get rid of it.

The point is this: if you try to key using the stinkin'-lousy H.264 codec used by DSLR's, you're going to have problems even under the best of circumstances. So give yourself a fighting chance! Use good lighting! Light according to Keylight's strongest suit -- a slightly DARKER background than otber keyers.

If you had access to a waveform monitor. -- which you DON'T -- the background should be at 65-75 IRE if the brightest spot on the subject is 100 IRE.

You CAN pull a good key using. DSLR video, but it won't be perfect. It's what you have to work with. But people do it.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 24, 2018 at 9:27:53 am

[Dave LaRonde] "
Understand that I have Not looked at everything in this thread."


Hey Dave,
Ya the thread got a bit long but the issue turns out to be that he WASN'T using footage straight from the camera but that somewhere in his workflow was getting re-re-recompressed files instead it seems. That's what he's tracking down now. Needless to say, nothing is gonna help pulling a clean matte in that case.


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 24, 2018 at 9:49:24 am

I will comment on everything else when I get off of work, but since this forum can't take over 100mb file size files, I had to shrink my footage to be able to be uploaded here. I took the footage into premiere and chopped the footage to 6 secs. When it comes to my work flow, I brought the footage from my SD card to a file folder then I uploaded it to AE. So the compression might be happening in the file folder or uploading it to AE. I didn't put it in Premiere first, only to get it ready for upload on here. If you guys want, I can put it in my Dropbox, from my SD card, and share the link with you guys? That way, no compression from Premiere is happeneing.


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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 24, 2018 at 10:17:26 pm

Sure upload a small chunk to drop box.
Just copying the file to a folder or uploading to the forum won't compress it. You could just stick the original in AE and render out a small bit at full quality. If its 8 bit footage you could render out as Quicktime animation best or AVI uncompressed - both of these won't introduce any compression (but the QT format will be smaller). If its 10bit or higher, set your AE project to 16bit and render out openEXR with floating point and RLE compression. This will render a bunch of stills.
You have to zip for drop box I think so just check your zip settings so that its just making a .zip wrapper and not actually compressing anything. The zip file should be just about the same size as the file you zipped. If its smaller you will know its been crushed. It may be a lossless crush but why take the chance when its the compression we're investigating.
Once we've got the unadulterated footage i'll send a CS6 file.



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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 25, 2018 at 5:27:03 am

So what I did was I uploaded it straight to AE from my SD card. It is 8 bit footage, so I submitted it as a Quicktime animation. I didn't zip it, as I can upload the clip straight to dropbox. Here is the link: https://www.dropbox.com/s/660rpfhuu1sz6eh/greenscreenfootage.mov?dl=0

I just wanted to make sure it had no compression. Thanks!


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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 26, 2018 at 8:02:24 am

Ok that footage is miles cleaner than the one you uploaded before. However it's still pretty noisy.

My preference for the color of green is more than just a personal preference.
In most CCD cameras (and ALL film cameras) the blue record is the noisiest, followed by the green and then the red (hence red-screen being the best, but unusable for humans - we once did a green-skinned alien movie and we used red screens - best keys ever!!!).
If you isolate each color in your footage to have a look (use the little kalidascope icon at the bottom of the main comp window and step through each color) you can see that red is pretty smooth. green isn't too bad either. but blue is a noisy blocky mess!. If your green screen has more blue in it (ie a darker bluer green) it will be noisier. But if you go too far the other way into the yellow greens you are getting into skin tones and blonde hair colors.

Also - was the camera locked off? There seems to be some breathing going on with the frame. You can certainly do moving camera green screen shots but with your wrinkles you are creating noise that has to be figured out in the compression, and with the slight movement the "lava lamp" effect on the matte edge will be more prominent. BTW stabilizing the shot at this point will only make that worse.
Use the heaviest/beastiest tripod/dolly you can afford.

Let me have a play with this and we'll see what works the best.



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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 26, 2018 at 10:09:16 am

So here's a comp with a few tricks in it (that are especially applicable to talking heads). Note that the project is in 16 bit even though you have 8 bit footage - this lets any color warps or level changes have a little more headroom instead of clipping.

In order to get rid of the blocky noise you have to crush the matte, this leads to helmet head. So we've added some hair back in at the edges. Its best to animate the head outline mask to follow the talent around (Rotoscoping). We haven't done this but you can keyframe the mask as her head will undoubtedly bob along has she talks. In this case it doesn't have to be a closed mask. We're just making a glowing line where the hair is at the edge (and then hiding that glowing line) and that will act as a soft rim matte to let the edge hair through. You could also do this with inner and outer feather masks if you like, but this will have fewer mask nodes to animate.

We tried degraining the footage but grain isn't really the problem - its the H264 blocks and general camera blobby noise that are the issue.

The main key is just a simple keylight key with some tweaking, I've also left on (but turned off) a few of the other native effects we tried to get rid of the noisy edge just so you might play and see what you get. We were getting better results handling the color and spill suppression on another layer unencumbered by the keyer. And the keyer controls, in this case, seemed a bit more of a big hammer than doing it another way. Just because you are keying a layer doesn't mean you have to "see" that layer. If it gives you more options you can pass another version of that layer through the key - it's just an alpha at that point. (you can even use a keyed layer as the alpha and then pass a copy of that layer with its own key through the original alpha - sort of applying they key twice.) Sometimes a more subtle, slightly transparent key, masked twice is better than crushing a single one too much. (but we didn't do that here).

Ideally you should pull multiple keys on this shot for the various sections of the screen that are differently lit, and then mask off those areas and blend everything together. Then animate those masks to follow the action. Many many many green screen shots have a rotoscoped mask traveling along doing everything from filling the center of the actor in with good color corrected footage, to separating well keyed areas from areas of different color or density, to masks that remove tracking dots or wires or other appliances that were in the shot, or running a clean edge along scissoring legs that blob together as the apex closes at each stride. Unlike those behind the scenes DVD's, it's not just sampling the green with the eye dropper and you're done.

Below the main key and its color element is another version of our edge hair trick - but this time with no mask. With it in behind the main alpha of the key, the wisps just poke out from behind the layer above. For both the hair edge layers: because the red record is so clean, if you shift that record to act as the alpha and then set all the others to red you get a cleaner less noisy element. (in this case we used luminance for each layer with red as the alpha just because we got a better signal to noise ratio)

Below that is the weird layer. The AltKey layer is almost the same as the top keyer, and again its turned off so we can pass another version of the main footage through. This time though we've blown up the main footage so that hair further in on the head (that is not interacting with the green screen) is passing through the edge of the matte. This fills in (even so subtly) hair at the edge and doesn't have any of the green screen noise in it (or color) and again helps get rid of the harsh edge needed to clamp the noise away at the edge of the matte.

Finally on the background we've added some noise to distract from the very noisy front element. (we did our usual dirty quick talent collapse to get rid of her since we don't have a clean plate)

There is one more problem you will have to animate the settings to deal with. It seems the talent is so close to the screen and the camera so close to the talent that when your crew moves about, the lighting on the screen changes. I can watch the matte get worse about 2 seconds before your clapper/loader comes into frame. In the two seconds before he appears, the screen gets darker and therefore the key changes and the settings may have to be keyframed to compensate. This darkening is him moving in for the kill and soaking up light as he comes - all things on set either reflect or soak up light. We also haven't done any garbage mattes (for instance the bottom right corner where the key is much worse than the rest at these settings)
The final issue is a little moire pattern in her left collar (stage left). That is nothing to do with the green screen and is just an interference pattern between her blouse and the pixels in the camera.

There are about a thousand ways to do a screen shot. When we get a toughy, normally we pass it around the shop and everyone has a crack at it. We don't share what we've each done with the next person so they take their own spin on it. Perhaps others will offer other solutions than we have done here (and this is by no means an extensive R&D project). In the end it has to be up to you because we won't know whats important to you. You may be fine with a clamped edge giving her a crisp outline as long as it gets rid of the noisy edge. You may prefer a bit of noise if it gives her a softer edge and some wisps. You may prefer a blurred edge to give it a "look" and thus remove the noise altogether. And every set up you have in your shots may require a different method due to lighting, colors, talent or movement.

12293_greenscreenheadcomp2.aep.zip



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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 26, 2018 at 4:34:38 pm

You file looks great. I love how it looks more clear and I did show my co-worker and she thought it looked great as well. I never would have thought to do it that way. Our teacher showed a movie trailer that used 100% rotoscoping, but they never showed us about it. If it is just a mask with a moving keyframe, then I think I should be able to do that. Is there a tutorial regarding soft rim mattes and inner and outer feather masks?

Is there a better rendering file to use for transferring and exporting?

Most of the tutorials I have seen show the Keylight and the cleaning the spill in the keylight and that is it. Our teacher kind of did that as well. Not many tutorials show the levels it takes to do green screen work, like your comp. The tutorial I showed in the first post is the one I used and it helped for the most part, but the masking the hair line and matting other things like you post is something I would have never done, since I am not used to using AE.

Since I am a one man person, I was the only one there recording, but I will be having the person farther away from the screen and the camera. I will have to zoom in some, but I will have them farther away from the screen and camera. I only had one light on the person and 2 on the green screen, so I will need to get more lighting. The way I came in to do the clapboard, there was not light, but I understand about me taking up the light completely, since I was in the way. My camera doesn't pick up that much light, so I know that I soaked up all the light.

I don't want noise, but I am stuck with it, since my camera doesn't pick up as much light as I wish it did. I am assuming it's my lens, but I just don't get enough. When it comes to my set up, it'll be able the same. It is a video bio for the vets, for clients and referring vets. I want it clean and bright and those are my issues. If I can get a better camera body, more lighting, and set up the vet farther away from the green screen and farther away from the camera, I think I would be able to chroma key it better, but as a one-man team, that is the only one that knows about video, it's difficult to get ideas and help, that is why I came onto here, after researching a lot.

I do want to thank you Steve for all your help. You have taught me some important things, that I never knew in the first place. I look forward to doing these techniques and tips, as I think I will be able to get a better/cleaner key out, if I follow them. My next goal is to get some more/better lighting. I am wanting to get some LED lights, that way I am able to shine it out more.

If I have any questions or need help, I won't be afraid to ask you, as you have been really nice and super helpful!


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 26, 2018 at 2:13:43 pm

I have a Manfrotto MT055XPRO3. It was locked off and it was not moving. Once I started recording and used the clapboard to sync sound, I left it allow until I was done recording!


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Mark Whitney
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 26, 2018 at 2:56:52 pm

[Steve Bentley] "Ok that footage is miles cleaner than the one you uploaded before. However it's still pretty noisy."

That's what I'm seeing as well.

Matt, what ISO were you using?


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Matt Dodds
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 26, 2018 at 3:59:15 pm

I am using ISO 400, since I know that I normally get lots of grain! I try not to go any higher!


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Steve Bentley
Re: Green Screen Dancing Edge Pixels (After Effects CS6)
on Mar 26, 2018 at 11:17:21 pm

Ok, at the risk of elevating the ire of the community and lengthening this topic....
I hadn't actually watched that youtube tutorial in the initial post until now (since you mentioned it again).
Where do I start.... I haven't yelled at TV for a while but that gave my lungs a good workout!

I never like being negative in these forums because it doesn't help anyone, and because there's never one right way to do something. And often, when investigating even dubious techniques, even us seasoned pros can learn a trick or two.

Buuuutttt.... There is just so much questionable information in that tutorial. So much so that the instructor doesn't seem to know how to use AE in some areas. At one point he decides to use another layer as a matte. Since forever we have this thing called track matte that lets you pass the layer below through the layer above in either alpha or luma mode. While his technique is not wrong , it sure is a long way round a simple every day occurrence, and his technique is one we haven't used since AE was called COSA. So that makes me wonder where the rest of the info has come from and his level of expertise.

Anyway getting beyond that little nit to pick.

The first issue could be classed a preference, but using full-red to check a key - any full chroma will overload your eyeballs and your monitor. You will not be able to see subtle issues in the matte edge with your cones screaming to turn down the volume and your monitor being pushed to the limits of its gammut. In addition, any two full-chroma primaries next to each other (red/Blue, Red/Green, Green/Blue) can vibrate in the eye (especially red/Blue - I can explain why if you like but its not important here)

His method for recoloring the screen to make it easier for Keylight to see.... Anytime you add a color correction or level trim or compression, or even change the color space, you are losing or transposing information. You can't make more of what was there you can only crush it or invent it. Its like yelling at a person with a hearing aid. It kind of overloads a delicate system put in place to detect subtle things and you end up warping or replacing the information.
When we do film transfers we go to great lengths (enormous lengths, these companies spend month getting LUTS just right to tease the most out of the footage) to ensure that as much of the color of the screen is preserved, because even in a $1500 an hour grading suite you are loosing or shifting information and every time that happens the key gets worse.
There are subtle little roll offs between the green of the screen and the person in front of it. The keyers are designed to pick up those subtle differences and work in magical ways to determine what is screen and what is human; pushing and pulling on feathered edges and gentle blurs, even keeping but desaturating greenscreen pixels and letting them play as foreground pixels. By changing the color of the screen you are forcing colors into those subtle areas in ways that are more heavy handed than a keyer would and without control of that roll off. A keyer doesn't care whether it sees a particular color, it only cares about the chroma separation between that specific color and things that are not. You can use keylight with green or blue or red, or beige or skybluepink if you want, but use it with the color that came on the virgin footage. You are also killing the grain structure when you stomp on the screen color - this is great for reducing the noise, but noise is detail.
Will his replace color technique produce a sharp key with less issues? You bet! Will it be the most accurate key and keep all the little feathery wispy details and show you his outline right to the last pixel of him? Not on your life. If you used that technique with something like water being poured into a glass (all on green screen) you would end up with a posterized mess.

Then there's the whole matte math done with, among other transfer functions, the Lighten. Instead of describing how lighten works across a range of uses, you just have to use it for a while in compositing to realize it has a very narrow niche. Try using it instead of screen or overlay or a few of the other blend modes that are used daily. It creates harsh roll offs which look sort of posterized. When applied to mattes or the product of mattes its not going to be the best and will surely wreck those subtle rollsoffs the keyers were designed to deal with. Then he adds a blur to overcome the harshness all his monkeying added. You could have probably added the blur to the initial keylight matte and then crushed it and come out the same. But again, its not going to preserve all the little edges that make a comp look real vs pasted on top. If you have harshened an edge and then softened it, you have changed that edge irrevocably, an no CSI type software is going to be able to resolve the original details again. ( I have a friend in Forensics who says CSI is is favorite comedy show, I'm starting to feel the same about this youtube video).

I'm sure there are situations where some of those techniques might be useful but to put them forwards as "here's how you pull a key", is doing a disservice to all the things keying software can do when used properly. And I think this shows in his final comps. Especially the guy with the glasses at the end. I don't have any clients that would accept that boiling bubbling key where the stem of his eyeglasses disappears.
Notice I'm not posting this rant to his youtube page. I only spouted because you are having troubles, and this video you brought forward is going to steer you wrong.



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