Green Screen on a budget

[David Scattergood]

Couple of frame grabs since capturing some test footage:

The first pic shows a frame before any keying had taken place - the tripod flori worked quite well (please feel free to tell me otherwise!). Perhaps may need to increase the wattage of the tube lights from 36w (x4) to something a little higher (although I'm aware that the screen shouldn't be lit too brightly) and I'll need to raise them higher on some sort of tripod (the zebra was fairly consistent up to the top 1/5 of the screen (where the light from the tubes fell off).
Could also perhaps sort out a few of the creases and maybe add a backlight (same type of light as the fill seeing as I have a flori only set up at the moment).

The second pic is my first key with motion (using Primatte RT, Blue & Green screen and Matt Choker) - slight concern over 'jaggies' which I hope are down to motion's lower rez view screen. I also found that some of the background (from a still/video) 'shone' through the hair occasionally!?!

The third pic is the key done in FCP - bit more long winded than Motion and seemed to get the image sharp, but I find there's an outline to the talent which isn't really acceptable for most backgrounds (bar the darker ones).

Appreciate you're all busy, but I literally have no one else in this environment in which to grab feedback.

Many thanks - you folks have really helped me get this far, where just a week ago I may have thought it impractical.

Cheers.

[Seth Bloombaum]

Those results aren't bad at all - your persistence is paying off, David.

Likely your Motion filter chain would benefit from a little chroma blur before the matt is cut - that should take care of jaggies.

Once again I am impressed with FCP's native filters - they really aren't bad for green screen work. I've had better results with "Chromakey" rather than "Green/Blue Screen".

Usually you'd want to use color bars as the background for key tests, as this will help reveal whether areas of the subject are keying (seeing background through the subject).

We've not really discussed your camera. If you have detail controls, you'll want to test with turning down detailing in the camera. This can help with the "outline" issue.

I think your screen lights are spilling substantially on the subject. You might experiment with barndooring off one of the screen lights - so you'd only get spill from one side. This has more to do with the look you like, but conventional thinking would be that side light from two sides connotes "studio shoot", from one side suggests more of a natural environment.

[David Scattergood]

Originally Posted by Seth Bloombaum

Those results aren't bad at all - your persistence is paying off, David.

Likely your Motion filter chain would benefit from a little chroma blur before the matt is cut - that should take care of jaggies.

Once again I am impressed with FCP's native filters - they really aren't bad for green screen work. I've had better results with "Chromakey" rather than "Green/Blue Screen".

Usually you'd want to use color bars as the background for key tests, as this will help reveal whether areas of the subject are keying (seeing background through the subject).

We've not really discussed your camera. If you have detail controls, you'll want to test with turning down detailing in the camera. This can help with the "outline" issue.

I think your screen lights are spilling substantially on the subject. You might experiment with barndooring off one of the screen lights - so you'd only get spill from one side. This has more to do with the look you like, but conventional thinking would be that side light from two sides connotes "studio shoot", from one side suggests more of a natural environment.

Thanks for that Seth. I'm fairly pleased with the results but want to push it till it's the best I can get it.

With the camera (JVC HD100) I tend to stick with Paulo Ciccone's Tru Colour 3 setting - that's another realm I've yet to seriously study (and I don't really have the monitoring equipment to pull off such probing). However I'll dig into the menu and turn the detailing down somewhat.

I'd set the lights quite close to the screen and a few feet away from the subject but I can where the spill is coming from now. I'm going to try and build some barn doors (a la kinoflo style) for these flori tubes - and good tip re the one side 'barned off' Seth, for the more natural look.
I may also use a backlight but this may not be necessary such are the keying results?

I didn't really use FCP's chroma keyer as much as Blue and Green Screen and Matt Choker - it's pretty good but I'm getting a pronounced outline and it looks 'cut out' rather than natural...trial and error for some time me thinks with both FCP and Motion :)

Massive thanks for the tips and advice once again.

[David Scattergood]

I've found the FCP workflow to be pretty decent actually:

* create 8 point garbage matte

* colour smoothing

* chroma keyer

It little more complex than the Motion method, but until I try that again I can't confirm which I personally prefer/believe has the better 'engine' for the job.

I've found it tough to achieve near on perfection - the main 'spanner in the works' is the touch of green surrounding the hair (for the main). Despite the tools available to eliminate this (spill suppressor etc) it's more than likely down to spill from the screen or screen lights (despite my best intentions of separating both screen and subject). Will try flags for the tube lights (4' ones at that!) and pick up a back light to try too.
If I were to require a 'sunny/bright beach scene' might I run into problems mixing a halogen (for the subject) with the screen flori's if both were fairly isolated? Can't think of a bright enough fluorescent tubelight for this purpose.

have attached the latest FCP frame grabs: the whiteish scene works fairly well but seems a little 'effected' rather than natural...I guess I haven't the tools nor skill to carry out the apple advert effect just now.

the second pic is a bit of a mess around for a beach shot - the green palm tree behind the subject masks some of the small amounts of green spill in the hair. Certainly understand the concepts surrounding matching 'talent' with 'background'.

Anyway - thanks all - bit of a crash course for me and apologies for the persistent posts, but it's probably good source material for other posters wishing to pick up the techniques.

Cheers.

[Richard Andrewski]

Not too shabby at all. Looks like you're getting good results to me.

[Michael Chenoweth]

David,

It's looks tons better - Couple of thoughts -

First of all, how are you measuring light on the green screen? Eye? Zebras? -

I think you could open up your iris a bit and get that screen to pop a bit more - Not sure you need that much more light on it. But it could stand to be a tad brighter - if that isn't an option, (FCP is different, I'm using Vegas) boost just the green channel while looking at a Waveform, try to get the screen to at least 60 ire. Not necessary but worth a shot to get the screen to a good level. That should take care of having to garbage matte it - I've not had to matte it in either Vegas or After Effects after pumping the green up a bit.

Poor man's spill supression - Vegas doesn't have it so I use this method - take your green screen footage and duplicate the clip - turn on the mask on the second clip and use that as an alpha channel to your green screen clip - only the footage of Elise should show through - nothing else -

Then take the green screen clip and desaturate the green completely. This will turn the green fairly grey (spill supression does the same) - because you have the Alpha matte working for you now, the green doesn't matter.

Voila, spill supression if the FCP one isn't working.

Other than that, if you flipped the footage horizontally against that exterior background, your lighting would match up pretty darn well. Shirt lettering would be backwards but you can see how the lighting works with what you already have shot.

All in all, it's looking really good. Not bad for shop lights. ;)

I just found a Husky 300 - 350 watt equivalent light at Home Depot (USA) - pretty cool but a little steep for the price. I may pick one up anyway and play...

http://www.toolsnob.com/archives/200...tripod_f_1.php

mike

[David Scattergood]

Originally Posted by Richard Andrewski

Not too shabby at all. Looks like you're getting good results to me.

Thanks Richard - you'll see I found those 4 foot tubes in the end. I'm going to pick up some slightly higher rated ones (I think they go up to 48w) but they're pretty bright as they are. Not sure it's possible to choose tungsten balanced flori's with these shoplights - possible to procure them?
Also - I don't suppose you created flags for this type of shop light Richard? :)
I may order your flags for a halogen worklight should I go that route.
In fact, I might try a 150w halogen (they're quite cheap) as either a fill or backlight (or both) - just in case I needed the 'bright sunny day' shot. As long as I separate the screen from the subject it should turn out ok?

First of all, how are you measuring light on the green screen? Eye? Zebras?

Zebra's - however checking my settings I had the zebra set at 85-95% - probably ok for the subject but I believe this should be lower (70%?) for the green?
The iris was set at around 2.8 i.e. only a couple of stops before it was fully open - the tubelights were set close to the screen but perhaps I should pick up some stronger bulbs (as I understood it, the screen shouldn't be overlit).

Yes - FCP has a still supression (not sure about Motion) but it's always good to try other methods - thanks for that workflow.

I'm pleased you feel the results are fairly decent - I'm quite happy with them but fine tuning is needed. It's a struggle to eliminate bits of green spill, mainly from the hair, and with further tweaking I'm seeing degradation of the talent image (noticed parts of the image 'fizzing' especially lettering on the t shirt).

Cheers.

[Seth Bloombaum]

Originally Posted by Michael Chenoweth

...Poor man's spill supression - Vegas doesn't have it so I use this method - take your green screen footage and duplicate the clip - turn on the mask on the second clip and use that as an alpha channel to your green screen clip - only the footage of Elise should show through - nothing else -

Then take the green screen clip and desaturate the green completely. This will turn the green fairly grey (spill supression does the same) - because you have the Alpha matte working for you now, the green doesn't matter.

Voila, spill supression if the FCP one isn't working....

I like it! Sounds like a great technique, I look forward to trying it.

Originally Posted by David Scattergood

...Zebra's - however checking my settings I had the zebra set at 85-95% - probably ok for the subject but I believe this should be lower (70%?) for the green?...

It's a struggle to eliminate bits of green spill, mainly from the hair, and with further tweaking I'm seeing degradation of the talent image (noticed parts of the image 'fizzing' especially lettering on the t shirt)...

David, you are getting in the zone! Yes, 65-70 on the screen is the right range, and you don't want it hotter because that leads to more spill.

Dealing with spill... get the subject further away from the screen (I know, you're in your living room, but this is how its done), reduce the size of the screen until it is just big enough, sometimes magenta backlight will help, and then post spill suppression. But subject-to-screen distance is primary.

On another subject, if you are looking for believable composites that will have your audience wondering whether the subject was actually on-location, matching the lighting setups is important. For example, if you were really using the palm trees shot as a bg, you'd want a hard light source high and to the right, some deeper shadows, add a fan occassionally to simulate island breezes, add some seashore sound efx and bird calls deep in the background...

OTOH, many times that we are using green-screen we're not so concerned with "realism", which does, after all, take substantially more work!

[David Scattergood]

Originally Posted by Seth Bloombaum

I like it! Sounds like a great technique, I look forward to trying it.


David, you are getting in the zone! Yes, 65-70 on the screen is the right range, and you don't want it hotter because that leads to more spill.

Dealing with spill... get the subject further away from the screen (I know, you're in your living room, but this is how its done), reduce the size of the screen until it is just big enough, sometimes magenta backlight will help, and then post spill suppression. But subject-to-screen distance is primary.

On another subject, if you are looking for believable composites that will have your audience wondering whether the subject was actually on-location, matching the lighting setups is important. For example, if you were really using the palm trees shot as a bg, you'd want a hard light source high and to the right, some deeper shadows, add a fan occassionally to simulate island breezes, add some seashore sound efx and bird calls deep in the background...

OTOH, many times that we are using green-screen we're not so concerned with "realism", which does, after all, take substantially more work!

I should stop watching Heroes...trying to match the almost seamless blending of blue/green screen there but on my tin pot budget :)

I was thinking earlier actually (inspired by Dean's chromakey) whether a fan might add that extra edge of realism (obviously not on full whack constantly....perhaps I'll save that for the 'speedboat' shot).

OK - I'll nudge the zebra down (by the way 'detail' in the cam is set a Min anyhow). I can see part of the fun (why else would we rack our brains over this?) would be realistically matching the background e.g. the aforementioned fan/hard lighting/shadows - it is indeed falling into place.

I was pretty tight against the wall filming though I guess I can move the subject a foot or two forwards (or use larger premises should the tests convince the client!).
I've actually just got hold of a much larger green screen today (£5 for a king size cotton sheet - had to order it in, not quite the bed linen colour of choice).

I will get a backlight - I know some use one some don't but I'll need if for other projects (interviews) anyhow.

*I've probably asked this a million times...and I feel like cocoa the clown keep on asking, so sorry folks, but:

I'm thoroughly satisfied with 4' flori tubes (more so with a tripod & flags for them) but where I to require a harsher light (sunny scenarios) could I get away with either a 500w or 150w halogen for the subject whilst using the tubes? As for the backlight, I could purchase another tripod flori (with the energy efficient lamps so I'd match the fill/key) or use a halogen for the backlight i.e. something a little bit more punchy.

btw - For me personally, FCP seems far more pliable and contains dozens more parameters than Motion for chroma-keying.

Thanks once more.

[Richard Andrewski]

Originally Posted by David Scattergood

Not sure it's possible to choose tungsten balanced flori's with these shoplights - possible to procure them?

It's possible but not highly likely. 3200K is pretty rare in 4 foot tubes. The closest you're likely to find commonly is 3500K and that might be close enough to work although you'll find that with the lower color temperatures, even the slightest changes are more noticeable than in the higher ranges of daylight and above.

Originally Posted by David Scattergood

Also - I don't suppose you created flags for this type of shop light Richard? :)
I may order your flags for a halogen worklight should I go that route.
In fact, I might try a 150w halogen (they're quite cheap) as either a fill or backlight (or both) - just in case I needed the 'bright sunny day' shot. As long as I separate the screen from the subject it should turn out ok?

I never created barndoors for them because they're just too big. A common type is either corrugated plastic. Something light and durable. Foam core is okay but is far less durable and more disposable. Eggcrates are the best though for controlling sidespill in any softlight including fluorescents. If you could find a shoplight with an eggcrate on it thats removable, that would be nice.

[David Scattergood]

^^ Cheers Richard - good idea - I've seen those synthetic i.e. non cardboard eggcrates around...I should develop an omelet addiction over the next few weeks in order to get enough of them!

As for the tungsten balanced tubes I guess I'll stick with what I've got then eventually start building up some pro lights.

Anyhow - thanks everyone, I saw the client last friday evening and he was more than happy with the results, which is good news.

I think they're after full body work so I'll need a larger location for one and perhaps that elusive back light and stronger fill/key - might be worth me picking those halogen worklights as a start.

Cheers all.

[George Kroonder]

Originally Posted by David Scattergood

I've seen those synthetic i.e. non cardboard eggcrates around...I should develop an omelet addiction over the next few weeks in order to get enough of them!

Not sure if you're kidding here...

Egg crate (in lighting): http://www.lowel.com/edu/light_controls/egg_crates.html

George/

[David Scattergood]

Originally Posted by George Kroonder

Not sure if you're kidding here...

Egg crate (in lighting): http://www.lowel.com/edu/light_controls/egg_crates.html

George/

Erm...no I was pretty serious George - I have to be on my budget!
Well, I've learned something again this evening - it's cool though as I'm not that hot on omelets :)

An electrician friend of mine has sourced some tripods used with flori tubes so that's a bit saved - I'll search for these 'eggcrates' (hopefully large enough for the 4' shoplights) and see if I'm in luck.
Cheers.

[George Kroonder]

There are also "egg crates" for 4' office lighting fixtures, so you may be able to work with those.

George/

[David Scattergood]

Are these additional pieces of kit rather than a whole new light (with built in 'eggcrates'?) That would be handy...I guess it would mean taking the diffuser off though?

I've just seen these:

http://www.qvsdirect.com/2-Lamp-Surf...-pr-16766.html

but they are pre built rather than egg-crate accessories.
I'll search around George - if I can source some (and soon picking up some free tripods off a friend) I'll have a very reasonably priced flori set up.

Well if you stick with a 2800K to 3000K fluorescent color temperature you can match well to the halogen worklights as that's the range they are in. As long as you match color temps well there shouldn't be any problem with green spikes or such.

I think Richard posted this on another forum but it answers my question re mixing halogens and floris - I've managed to source a store which sells different temp flori tubes (3000k to 5200k daylight tubes). Perhaps not so important for the screen as I'm lighting that seperately but if I were to use the CFL flori for the fill/key I could pick up either a 150w or 500w halogen worklight for the back light (which I'll use for non green screen lighting set ups). The 150w clamp lights (is 150w strong enough in a smallish room set up for a back light?) retail at around £12 so worth a go.

Cheers.