DIY LiteRing Chroma Key POC

W

wheatgrinder

Hey all,
the other day I got intrigued by the idea of crafting my own version of the light ring based chroma key systems.. I did some digging..

If you dont know what Im talking about, check out the high end reflectmedia

http://www.reflecmedia.com/education/media/video-gallery/litering-camera-action.htm

$2500 for a setup..

A better priced knock of can be had at

http://www.bhphotovideo.com/c/produ...0_KIT_CKL_200_Dual_Color_Chromakey_Light.html

The trick here was figuring out what the backdrop was made out of... retroreflective material.. once I got that far, I found a 3M supplier that sent me a 12" x 9' sample.. pretty cool, until today I wasnt sure I had the right stuff.... so I spent a few minutes, with what ever leds I had lying about, I set this up in about 15 mins..


(sorry about the strangeness in the first few seconds.. )

https://www.youtube.com/watch?v=86XH2cypiNA

Here is a quick keying attempt.. Iv never done keying before..

https://www.youtube.com/watch?v=UxlB_E-m6o0

Now, that fabric is very expensive, about $35 a yard, so its still too rich for my blood. But you can save a LOT of money doing it your self if you want to try this. I am looking for a knock of supplier out of china....


EDIT: So the shadow was made WORSE by being balanced for sunlight, and not florescent... in further tests, the shadows are just another shade of green (not brown like this example) and caused only small issues in keying.
 
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@michaelmanch
Hi, try not to be offended at my luGOOBrius friend. Hes just bein a smart a@#! Aint that right Goob?

Hey, if your in a hurry and have lots of money.. check out datavideo, or the other big brand I cant recall.. I did note that on the datavide site, you could BUY on loan an entire setup and get refunded after you evaluation.. or something to that affect. though I bet thats a slow process..
 
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I can be an asshole at times. I go to work and hang out with a bunch of guys that have nothing better to do than pick and make fun of each other. I guess it kinda rubs off.
 
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gooberman said:
I can be an asshole at times. I go to work and hang out with a bunch of guys that have nothing better to do than pick and make fun of each other. I guess it kinda rubs off.
Click to expand...


I miss that most about being in the construction trades. Lots of dude on dude time.. now days, I work in an ultra diverse cube farm, smart assery is held in low regard, but Im so good at it!.

Aint love grand
 
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previous attempts discovered

I just discovered that there have been two previous attempts to craft a homebuilt DIY method of combining the reflective fabric and a light ring which have been documented online.

This individual sold kits previously to users on the HV20 forum:

Cheap 'Chromatte' Reflective Chromakey material - any interest?
http://www.hv20.com/showthread.php?28349-Cheap-Chromatte-Reflective-Chromakey-material-any-interest

On another forum an individual has provided information about his experiments and the results:

DiY Retroreflective Green/Bluescreen
http://hbsboard.com/index.php/topic,1337.0.html

Unfortunately, this suggests a duplication of effort by wheatgrinder and others but I guess you can count it as a learning experience. Perhaps there were some refinements or changes that produced different/better results, particularly with the light ring. Seems like there's enough information for me to proceed on my own. Best wishes.
 
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So the wife and I sewed up our first 10'X8' (approx) backdrop with the Chinese fabric. We did a few mini test sews and though a french seems should be stronger, the flat seem worked just fine and is about the easiest seem to sew.

I gaff taped one end of the fabric to a 11' piece of steel pipe I had around, slung some straps from the first floor joist in the basement. My basement has a 9' ceiling so perfect fit.

So now I have a huge green screen in my basement.. fun! I did some quick testing, but I need a bit more control and better documentation.

There is one disappointment, and its with the technology I think.. Having fabric on the floor just doesn't work. If the angle is too flat, the light just doesn't bounce back.. If I raise the tripod and point down at the floor then I can get the green, Iv not measure the min angle yet, but Id guess its around 110 or more.. (camera at 90deg is perpendicular to the floor)
 
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I'm coming to realize that this tech is not the answer to EVERY green screen situation. For example, ECU's are just impossible. The green light is coming from the neighborhood of the lens and eventual it overcomes and lighting you have on the subject.

It works outside, but probably a lot more portable to just use traditional green screen in good out door light, now night time.. different situation all together, this tech would work MUCH simpler than trying to light a big green screen at night..
 
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So, last night I did some more structured testing. For one, I took off all my cool lens goodies, i.e. the letus 35mm adapter and cannon lenses.. wow, what a difference. The quality of the Green screen plate is way improved, not that it was bad before, but now its crisp and clean.

Here is the plate: (aint I a bad a#@!)
https://www.youtube.com/watch?v=IPt9_CTZ7OU

and here is my fun comp (not my best work.. no light spill from the muzzle flashes etc.. )
Kilmer Im not, but, maybe a Deniro of you squint a bit... :)

https://www.youtube.com/watch?v=iFr-5OEO-Vs


FYI: The glasses are my magnifiers for doing miniature work.. thought they looked cool on the character..
 
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whats surprising is how little I do to get it to work. Really nothing..

Steps:

  • Set up the Chrom-A-Matic Reflectifying backdrop
  • Turn OFF the Chrom-A-Matic Diodic Emitter
  • Set up the shot, light as desired.
  • Set exposure on camera and lock.
  • Turn ON the Chrom-A-Matic Diodic Emitter
  • Push the red button to make movie on your camera.

"cool names eh?"
 
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I should put together an HD clip of different scenarios so people can try keying the footage themselves. Would be great if I had some traditional green screen footage to compare or replicate... and references?

the glass would be interesting, certainly right on would NOT work, but a small angle Id have to try.. also depends on how close the glass is, dirty class would likely be a problem if it was close to the emitter..

Seems hair would be the same as any other green screen, thats more a keying problem then the screen you use.. agree?
 
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That'd be great, interesting to have a go. I guess hair would be the same as most other green screens when keying, I was just curious as to if this system made it any easier. A little difference to the eye can make a huge difference in post when shooting with a normal screen, thought your kit might be a similar jump in improvement.
 
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I think a traditional green screen, kinoflow with green bulbs, etc, in the hands of an experienced professional would still be better than anything I can do with this system.

The advantage I believe is that an inexperienced person can get pretty good results with a minimum of errors. As most of us use GS on occasion, having a system in your back pocket for a few hundred bucks that can get you 80% the quality of a much more advanced and expensive traditional green screen setup\specialists is a good investment.
 
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wheatgrinder said:
Seems hair would be the same as any other green screen, thats more a keying problem then the screen you use.. agree?
Click to expand...

Not necessarily, the typical problem with hair is the green light reflecting back at the hair from the sides... since the background here only directly toward the camera, the off-axis light is eliminated, and I think that is the majority of the problem with keying hair, etc... now, transparency is still interesting to me.
 
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