Green Screen Advice

[David Scattergood]

Hi David.

Motion gives a fairly good result. I first use the Bezier Mask Tool (garbage matte) to get rid of any extraneous parts of the frame and leave only those parts of the greenscreen that are very close to the subject. This can help in cases where the greenscreen is unevenly lit.

I then use the Primatte RT keyer, which comes supplied with Motion 3.0.2, for the keying process.

Cheers David - I'll give motion a go in that case, although by the sounds of it I'm limited in as much as I have Motion 2 only - is there a likewise keyer (albeit not as proficient) in Motion 2?

David, if you own adobe after effects 7 or later it comes with the
Keylight keyer for free.

This plugin is VERY robust and pulls excellent keys even with
straight HDV footage.

I would definitely recommend keying in After Effects or Motion if thats
what you have. I've tested MANY plugins and I have not yet found
one that works well in FCP. The keying is ok, but not great and never
is in my experience. Doing it in a compositing app is really my only option
for good keying even for scenes with someone wearing glasses and getting that transparency just right.

I seem to be in a minor group of none AE owners on these boards - many things point to owning After Effects! I once toyed with getting Shake, but I feel AE would make for a more practical purchase.
I've also produced good results (mainly title sequences) on Live Type which I was surprised about (initially thinking it was just a huge folder of animated titles)...anyway I'm off on a tangent. Hopefully carry out some tests (not fully lit) later today - hopefully with mistakes made I can work backwards and help eliminate them...screen grabs to come folks :)

Really appreciated your comments.

[Brian Luce]

Originally Posted by Tim Dashwood

Here is my #1 tip for green screen work: counteract spill with 'minus green' gels (magenta.) .

What's a good light to use with the orange gel?

Fresnel?

[George Kroonder]

Originally Posted by Brian Luce

Fresnel?

Preferably softboxes, flo's or open face lights. Cycs or anything else that will give you an evenly lit CK-screen.

The filter is just there to reduce the red and blue output, leaving more green, for a higher contrast between the primaries for an easier key.

George/

[David Knaggs]

Originally Posted by David Scattergood

... by the sounds of it I'm limited in as much as I have Motion 2 only - is there a likewise keyer (albeit not as proficient) in Motion 2?

For all I know, you might even have Primatte RT in your version. Why don't you find out? In your version of Motion, select the "Add Filter" icon and then click "Keying" and you should get a drop-down menu displaying all of the available keyers for your use.

[David Scattergood]

Originally Posted by David Knaggs

For all I know, you might even have Primatte RT in your version. Why don't you find out? In your version of Motion, select the "Add Filter" icon and then click "Keying" and you should get a drop-down menu displaying all of the available keyers for your use.

Cheers - as it happens I'm currently dismantling Motion this week (reinstall etc)...over the past few days it has grounded to a halt - absolutely no idea what's wrong with it (have trashed prefs etc). Shame as I was pushing it's boundaries on a couple of projects :(
Once it's back up (hopefully this evening) I'll check it's keying capabilities.
Thanks.

[George Kroonder]

Originally Posted by George Kroonder

The filter is just there to reduce the red and blue output, leaving more green, for a higher contrast between the primaries for an easier key.

Sorry, must have still been asleep... The orange gel you could use on the hairlight to counteract spill, but I've never used this. Using a fresnel for a hairlight makes sense ;-)

The Lee 138 I mentioned in an earlier post is what I blather about in the quoted text, and is used to reduce the red/blue primaries on the bg.

George/

[Brian Luce]

Originally Posted by George Kroonder

Preferably softboxes, flo's or open face lights. Cycs or anything else that will give you an evenly lit CK-screen.

The filter is just there to reduce the red and blue output, leaving more green, for a higher contrast between the primaries for an easier key.

George/

I think you misunderstood, I'm talking about the backlight with the orange gel. Not the light for the green screen. Would a 150 watt fresnel make sense? set up pretty high?

[George Kroonder]

Hah! I must be psychic or delerious from the heat over here; how else can I answer questions before them being asked?

George/

[Bill Mecca]

I've just begun working with some green screen, with a variety of results.


I remember seeing the LED ring lights a few years ago at the DV Expo East (which seems to be history) and it was intriguing, but someone correct me if I'm wrong, but it won't work with teleprompters.

[Brian Luce]

Originally Posted by Bill Mecca

I've just begun working with some green screen, with a variety of results.


I remember seeing the LED ring lights a few years ago at the DV Expo East (which seems to be history) and it was intriguing, but someone correct me if I'm wrong, but it won't work with teleprompters.

That's true.

[David Scattergood]

You probably already know this but the key (no pun intended) is to make sure that you don't light your greenscreen too much and that you light it evenly! We used to use cheap halogen worklights at a very high angle to the camera and that worked very well, most of the green spill hit the floor then. Also, keep your subject about 3 to 4 feet away (or more if necessary) from the greenscreen, that will also reduce the spill. Doing this made it so we didn't have to do very much (if any) color correction in post.

Going back to a more budgeted affair (as much a the LED ring system look promising) I was picking up some materials in a hardware store a short while ago (for the green screen frame as it happens) and noticed those work lights.
I'm surprised at just how cheap they are - £12 ($24) each.
Bear in mind that I have no lighting rig to call my own and that I'm currently testing possibilities, might I get away with a few of these (and apologies for veering into lighting questions)?
They stock mains voltage (and transformer types) halogens at either 500w or 150w - I'm presuming for a small cost I could use the 150w to light the screen and perhaps one or two 500w as fill and back (unsure as to how I would manage a key light) - I'm assuming gels would work the same with halogen lights?.
I was sowing green cotton sheets last night...at the very least I've learned how to sow!

[Bill Mecca]

David,

I'm interested in the frame you mentioned. could you share more detail?

I have one of those collpasible/pop-up blue on oneside green on the other at work, just used it this week(still trying to master the green screen thing), but have some green fabric at home and have been trying to devise a support system for it.

if i get chance I will convert one of the videos and post it along with pictures. I still had some spill that I couldn't quite control, but the "client" was very pleased with it. Using Avid xdv 3.5.3

[David Scattergood]

Originally Posted by Bill Mecca

David,

I'm interested in the frame you mentioned. could you share more detail?

I have one of those collpasible/pop-up blue on oneside green on the other at work, just used it this week(still trying to master the green screen thing), but have some green fabric at home and have been trying to devise a support system for it.

if i get chance I will convert one of the videos and post it along with pictures. I still had some spill that I couldn't quite control, but the "client" was very pleased with it. Using Avid xdv 3.5.3

It's basically conduit and associated 'conduit paraphernalia' i.e. elbows, t 'junctions' and hope for the best!
I'll post the link underneath (it's a US site as it happens) - it's worth a punt and will save some $'s but I can't as yet confirm it's practical use...some of the parts I couldn't get hold of (cross/4way junction - had to screw two elbow joints together in the end) and make sure you use wide enough conduit (anything below 22mm will probably collapse as soon as you add green screen). Also, although it doesn't mention this on the site you might need to keep it around 6 foot and perhaps have a third pole (at a 45 degree angle) to keep it sturdy.
If mine works ok I'll post the pics of it 'in action' so to speak.

linkie:

http://www.stormforcepictures.com/ho...reen.php#extra

...right those worklights...bit of muslin over a frame for a softbox and I'm hopefully good to go :)

[Bill Mecca]

Thanks for the link, that is kind of what I had in mind. I love PVC!!! LOL

work lights run hot so I would beware of the muslin.

I saw something recently where someone lit the green screen from behind. Don't know how well that would work, but I give them credits for creativity.

I got the video uploaded, no audio. I still have to get the pics off the camera hopefully this afternoon

http://www.youtube.com/watch?v=Mt38ZDMKV4M

It goes on and on without sound, but you can see how it came out. I used some small flourescents to light the screen and even with hot spots it keyed pretty well. I did wind up leaving the overhead lights on in the office, and that may account a bit for my being a tad washed out compared to the background. I had an Arri softbox for a key and used a reflector as the fill, an arri with straw gel for backlight.

[David Scattergood]

Had a hectic few days sorting out a pretty budgeted lighting set up and making sure the screen was taut and even (tapped in ringlets into the material down both sides so I could 'rope' the cloth).
Took the advice on the photon boards and went the flori route, which so far seem ok. Mains wired 2 twin flori 4' tubes* today as the main screen light and will be using a tripod based flori for fill/key (making sure there is no spill onto the screen).
Never really been keen on this type of light (a real cold and clinical look!) but seems to work ok in this scenario.

The tube lights need to be raised* as they are not quite hitting the top of the green for a full, even look (I'll shoot below this).

*if anyone knows of a suitable tripod/stand solution for these 4' lights I'd be most welcome (can't find any for love nor money...looks like plywood options then :) )

Just about to shoot a minute or two test footage, so here's a couple of snaps of my home made 'kinoflo green screen stage' :)

http://farm3.static.flickr.com/2283/...acfd57.jpg?v=0

http://farm3.static.flickr.com/2248/...19785d.jpg?v=0

comments always welcome!
cheers.