material green and blue screen set-up

[ScottKane]

i found this in a site but it says for old blue screen? i dont know check it out here http://www.vce.com/bluescreen.html

i read this:
Sources of blue/green screen:

Materials: Best materials for blue or green screen for rent are the Digital Green or Digital Blue spandex material available from Composite Components (http://www.digitalgreenscreen.com/prodindex.html). This provides the best reflectance of the desired color. The "economy" method is the old "Chroma" Green and "Chroma" Blue or Tempo screen which is a spongy material available for rental. This material is not preferred.

[JohnnyRandom]

On the cheap... By a roll of chroma paper. Usually comes 9 feet wide and runs any where from $40 to $200 US depending on the length. Works pretty good for what it is. Comes in blue and green. You can get narrower widths too.

http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=45551&is=REG&addedTroughType=search

[erilaz]

If you want it on the cheap, try not to use it at all except where absolutely necessary. If you're just comping a small area on the screen (like a building sitting behind an actor's head), only bluescreen that area.

[kk01]

thank you very much for your surpport...I appreciate it..Hey! Johnny I visited the website you gave to me http://www.bhphotovideo.com/bnh/con...oughType=search and I did like the chroma paper....my only problem is how do you mantain it...'kk'

[JohnnyRandom]

What do mean by maintain it? The rolls I have bought in the past come on a sturdy roll wrapped in a plastic sleeve inside a cardboard box. I usually unroll what I need use it and roll it back up and repackage it. I have hade the my current roll for over 4 years now and have only had to cut a couple of feet off of it due to a tear.

It is pretty strong paper, with a little care it should last you a long time.

Savage also makes a background stand (a couple of colapsable stands and a crossbar) runs about a $150 works really well.

It is also possible to just cut a piece off of the roll, head to the hardware store and buy some 3/4 or 1 inch PVC sprinkler pipe (1 inch is a bit more rigid) and gaff tape the cut piece to that, run a piece of rope through the pipe and hang it from the ceiling (if you have something to tie it too).

You really could easily build a BG stand entirely with PVC pipe if you were feeling ambitious:)

[explorer-pl]

i have something in material, but i don't know what it is anymore. but i most commonly use sheets of green a4 paper. this is flexible, and the results are quite good. the only thing you need to be careful with is when sticking them onto some window and lighting them from behind. you have to watch yourself not to overlap the sheets, because you'll end up with some not key-friendly dark green areas.

here are some test shots of what i did using this paper sheets. they still need some work, but the idea it there. each one of them was done in few minutes.

http://bruteforce.polygon.pl/blog/category/testdrive/

this site is an official production blog of my personal project im working on. and this is the official movie site: http://bruteforce.polygon.pl/

it's in polish, so if you're interested in descriptions i did for the movies i suggest using babelfish or some other linear translating system.

i hope you'll like it. oh. and i'd be happy to see some votes from you guys. no registration required to post a vote ;)

[beenyweenies]

Hello guyz,

I am trying to make my green and blue screen set-up....but I dont know what material to use...can someone please recommend a material to me....please note, I am on a budget....

Regards,
'kk'

PS: Just to know...does pure cotton material work...

If you want to go cheap but not super cheap, Amvona has a pretty good option:

http://www.amvona.com/v7/shop/?page=shop/flypage&product_id=2668

The nice thing with this setup, which I own myself, is that it's pretty big and pretty easy to do full body work. This is because the material is long enough that it will cover a 10' wide X 10' high wall and still extend out 6' or so onto the floor under the actor.

The greenscreen paper is ok for very basic work, but compositing work is all about the background being pure, saturated green. Paper reflects a lot of light and loses saturation as a result, whereas the fabric is not so reflective.

[JohnnyRandom]

BW thanks for the link:thumbsup:, just ordered some:), be honest the price isn't bad at all without the backdrop support. Just ordered 10x24 for $71 bucks. How durable is it? for that price not too worried but curious.

Alot of the other farbic backdrops I've seen for that size were running anywhere for $400-$1000 bucks, not really to stoked about dropping that kind of coin on that just yet...


I agree paper is hard to work with for sure, a lot of spill from it, but is is cheap and disposable. Anyway thanks again

[beenyweenies]

BW thanks for the link:thumbsup:, just ordered some:), be honest the price isn't bad at all without the backdrop support. Just ordered 10x24 for $71 bucks. How durable is it? for that price not too worried but curious.

You won't be disappointed. The material is thick enough to be durable and opaque when hung, but not so much that it's hard to work with, like folding and storing, etc.

It's pretty amazing to see this thing unfurled, it's very big (especially for the money). It covers a large enough portion of our soundstage that we can shoot from any camera position we want without having to do a lot of garbage mattes in the comps, which means $$ in bank.

[kk01]

I really appreciate your kind gestures and I wana say thank you for all your comments. I visited the website i.e www.amvona.com (http://www.amvona.com) and I saw their chroma background products. But, somehow I just have to make a choice but I dont think going for paper background will not hack it as you guyz have empahsized.

I'd like to know one thing and that is lightning for chroma-shots. Whats the idea behind lights in a chroma shot? Which should have more light?...is it the subject or the chroma background. When you say highly saturated chroma background...are you saying that light should not be able to pass thru' them (almost transparent) or what? Or should it be very thick. Also, is there a kind of meter you can use to read the amount of light on the subject or the chroma background...

I really need to this facts. Will be glad to read from you guyz soon...thanks..

Regards,

'kk'

PS: I guess this is the 2nd time I am seeing a chroma-background made from muslin fabric.

[explorer-pl]

I agree paper is hard to work with for sure, a lot of spill from it, but is is cheap and disposable. Anyway thanks again

well... its not that hard you know. you just need to prepare yourself the right way. try it once, and then you'll know what to do. here is the best result i've got so far from using the paper: http://bruteforce.polygon.pl/blog/2007/01/24/steward-i-brakujaca-kwestia/

theres a "play now" link at the bottom of the post. just above the comments. check it out and please tell me what you think by replying here, or by voteing :)

here the monitor screen was covered with the green paper: http://bruteforce.polygon.pl/blog/2007/01/22/greeny-i-screeny/

this still needs to be worked on. if you look closely theres some junk around the edges and on the computer's case... but its a good starting point i think.

finally... here is the link to the first test of using green paper on the windows and putting some light behind it: http://bruteforce.polygon.pl/blog/2007/02/18/helikopter/

just wait till it loads and you'll be able to see the movie before and after pre-postproduction :)

[kk01]

It's not in english...and you also you strayed away from the questions I asked. Anyways thanks..

[explorer-pl]

thats right, but i thought you'd be interested on the results from keying green paper

[JohnnyRandom]

well... its not that hard you know. you just need to prepare yourself the right way. try it once, and then you'll know what to do. here is the best result i've got so far from using the paper: http://bruteforce.polygon.pl/blog/2007/01/24/steward-i-brakujaca-kwestia/


Yep, I know I have been using that roll of paper for over four years:) but as mentioned the paper is more reflective than a fabric, plus the paper is to way thick to use backlighting, as you did.

I have learned how to light that specific paper, and to be honest I would rather use the fabric that BeenyWeenies mentioned. The cost is the same as the roll of paper...do you understand?

Back to topic:
There are certianly a hundred ways to do it but I can give you the basics for a "talent standing in front of the screen" type shot. Probably the most common.

First light your greenscreen so that light hits evenly everywhere (that would be ideal anyway), make sure there aren't any hotspots. Large tube flourescents (office lighting) work well, we're on the cheap right?

Second setup a keylight for you subject. From either the right or left and just off center or more depending if you want any facial shadowing. I use a softbox for this, but it isn't necessary.

Third add a backlight the illuminate the talents backside, this helps give you a nice hard edge between the talent and the greenscreen. You don't needs this light but it sure helps when you keying out the screen.

Fourth (if you want) add a hairlight or other light for emphisis, usually smaller lights with a narrow more focused beam.

Really alot of the specific lighting really depends on what your going to use as a background.

The above is for a basic studio indoor shot, if your planning to use an outdoor background, or say a room with windows, your going to need to imitate the lighting of the background as closely as possible to make it look believable.

Take into account were all the light sources are coming from in your background and try to mimic them.

[kk01]

Thank you so much John...you answered my question more explicitly..I know somehoe, that lights play a very important role in green/blue screen setup.

Talking about fabric...what kind of fabric will you describe is great for the purpose...silk, chiffon, cotton e.t.c. It's so right now I am really on a tight budget.

Thank you very much guyz for your contribution...

Regards,
'kk'

[JohnnyRandom]

No worries kk01:)

Arri Lights has a pdf out that is really pretty good about setting up different lighting scenerios. It doesn't deal with greenscreen specifically but it is an excellent primer on lighting.
http://www.arri.com/infodown/light/broch/arri_lighting_handbook_english.pdf

The link BeeneyWeenies posted was fabric, muslin (fairly typical for backdrops comes in all weights/quality, it is generally what determines the price), I haven't received the one I ordered yet so I can't tell you that much about it, other than it was very inexpensive.

[beenyweenies]

Lighting is actually FAR more crucial than the material used, as the screenshots posted upstream show. Here's the lowdown on greenscreens.

Most keying applications look for pure green in your image and "remove" that color to create your matte. Pure green means it would register as 0 Red | 255 Green | 0 Blue if you took a color sample of it in AE.

Over / under lighting a greenscreen causes the hue AND saturation to change dramatically. When the screen is overlit it takes on more of a yellow tint and when it's underlit it takes on more of a blueish tint. What usually happens is people get a hotspot in the middle with falloff toward the outer edges, the result of using one big light aimed right at the screen. This means undersaturated yellows (the hotspot), oversaturated blues (the falloff) and maybe a thin ring of actual green.

This forces you to tell the keying application to "look" for values beyond pure green. As it widens the range of color it will consider keyable, it will begin to remove color values present in skin and other materials (the underlying hue of most skin types is green). As a result, you have to choose - resort to mechanical fixes that degrade the quality of your edges, or start rotoscoping (have fun!).

Poor keys stand out as having very hard or extremely mushy edges around the characters. It's easy to brute force the settings in a keyer to get similar results, but neither looks natural or real. you should be able to cleanly key the image at near-default settings and retain detail like fine hair, all with natural edge feathering that matches the shot. This is easy to accomplish with a well lit screen.

Here's a cheap and easy way to know if your greenscreen is lit properly. Buy a cheap, pure green camera filter at a camera store (like $10). When lighting your greenscreen, occasionally put the lens to your eye and hold up a piece of white paper between you and the greenscreen. The white paper should seem to disappear into the screen once it is well lit. The reason is simple:

Pure green (the filter) plus white = pure green
Pure green plus badly lit greenscreen with a bit of blue hue = NOT pure green.

Once your backdrop blends with the white card somewhat nicely, you're good to go. The point is to spend as much time as is needed on the lighting to get it right, so that you don't spend weeks in the studio trying to get a good key, or worse yet having to reshoot. It is this frustration that has led me to spend the extra money to get good gear. This includes:
- 2 large fluorescent lights (http://www.flolight.com/) made for video use for lighting the greenscreen. Fluorescents create a very soft light that helps eliminate hot spots and falloff but you MUST use video-friendly fluorescent tubes.
- A large backdrop stand and cloth screen (http://www.amvona.com/v7/shop/?page=shop/flypage&view=1&product_id=64)
- Sandbags (http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=421396&is=REG&addedTroughType=search) to anchor the stand, allowing me to stretch the cloth tightly with clamps and avoid wrinkles
- A set of Arri lights (http://www.bhphotovideo.com/bnh/controller/home?O=4965&A=details&Q=&sku=72020&is=REG&addedTroughType=categoryNavigation) for illuminating the subject.

I also monitor the shoot via DVRack (http://www.seriousmagic.com/products/dvrack/) hooked up to a laptop. This allows you to sample the color values right there on the spot and know for sure what you're getting.


Sorry for the long, rambling post!~

[kk01]

I really dont know what to say...but this is more than enough for me to understand how to set-up my stage for green screen or blue screen...thank you very much guyz...I trully appreciate the time you have spent teach me how to do this properly...WOW!...

This is really great I must confess...thanks once more...

Regards,
'kk'

[JohnnyRandom]

Here's a cheap and easy way to know if your greenscreen is lit properly. Buy a cheap, pure green camera filter at a camera store (like $10). When lighting your greenscreen, occasionally put the lens to your eye and hold up a piece of white paper between you and the greenscreen. The white paper should seem to disappear into the screen once it is well lit.


Dude! Ramble on, that is a great tip!:thumbsup:

[kk01]

John after reading/digesting your message properly, I asked myself some questions and tot you were in the best position to answer questions...

First of, where will the flourecents be placed...behind the screen, above or in front of the screen and can't I use normal flourecents used in homes.

Secondly, you said you use sandbags to hold the screen to the floor to avoid wrinkles, what will happen if I want to capture the total frame i.e a long shot of the talent standing or maybe dancing. Also in this case, how do Ilight the floors...were will the florecents be placed.

Your tips were great and I appreciate. I also appreciate beenyweenies link to the pdf light handbook by Arri...thanks beenyweenies.

I guess that should be all for now...thank you very much...'kk'

[JohnnyRandom]

John after reading/digesting your message properly, I asked myself some questions and tot you were in the best position to answer questions...
heh, thanks I'll try...
you said you use sandbags to hold the screen to the floor to avoid wrinkles, what will happen if I want to capture the total frame i.e a long shot of the talent standing or maybe dancing. Also in this case, how do Ilight the floors...were will the florecents be placed.
That was BW :)

to capture a full frame you'll need a large screen... you maybe better of using paint, paint the walls and the floors with it...if you have that option (that can get expensive too though, it's around $50 a gallon), the sand bags are there to hold the base of the background stands, you can use gaff tape on the floors to strectch of the material.

Yep office fixtures:

http://images.lightinguniverse.com/img/l/313/313_fss240-c.jpg

You can either put them above (hang them from the ceiling) or the sides or both...

A quick and dirty example: HERE (http://www.4rand.com/test/lightsetup.png)


(http://www.4rand.com/test/Lightsetup.png)

[kk01]

Johnny, after reading your message, I was begining to feel I was in a class...say a film school...lol!

Anyways thank you very much for the post...I have really learnt a whole lot about keying screens. Thanks Johnny....I appreciate everything...

Regards,
'kk'

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