chroma keying cameras

[Marc Poirier]

Thanks for the info.. sometimes we need to shoot in places where space is an issue and being able to gain the 3-4 feet of extra space is sometimes good…

will look into it..

regards,

Marc.

Thanks!

Markyyyy

[Mark Suszko]

I was pretty sure he was talking about reflecmedia when I read the first post. Reflecmedia works, NFL uses it, from what I hear. But it has up and down sides. The down sides include:

Price. The cloth is just really expensive, especially in larger sizes. The cloth contains retro-reflective glass beads that bounce the ring light back towards the lens. You might be able to simulate the same thing with scotchlite fabric or road paint, but it will be way more expensive than latex flat chroma blue or green. I can wrap an entire studio in chroma blue or green fabric or paint for the price of an xtra-large sheet of this cloth. The price of the cloth is what held this system back from becoming a huge success with great market penetration. At the same time keying software has improved so dramatically that you can do way better with blue or green cloth now.

But because the whole principle of the thing is to only bounce back a keyable blue or green directly back to the lens, if you want to key a much wider area, the ring lite becomes a limitation as it only shoots light straight ahead. The sides of your shot will get less and less light from the lens ring illuminator the wider you go, also the farther back you go. A regular chroma background can be at almost any distance or angle and still work if it’s lit ok.

The ring light is also a problem if you want to put a teleprompter in front of your lens, it reflects in to the splitter mirror and the mirror attenuates the ring’s output as well.

Meanwhile, software gets more clever. My wife’s imac isight camera comes with a remarkably good live keyer effect in it that uses DIFFERENCE KEYING. You turn on the keying with a mouse click, step out of the camera shot for a second so it can grab a clean plate of the room behind you, then you sit back down and bam, the imac can put you live into most any static or moving backdrop you choose. Some included with the mac were the Eiffel tower, a tropical beach, and a roller coaster car in motion.

I expect to see more of the difference keying trick appear in consumer and prosumer apps.

I think it was some MIT work I saw online where they have a method of capturing the entire frame of a shot in perfect sharpness and then let you roll the depth of field control anywhere you like, like you had a tilt-shift lens in post.

Here’s my blue-sky idea: I can foresee using z-depth cues for future keying technology. For example, we know our image sensors can see IR wavelengths and today we add filtration to the sensors to screen it out… but what if we remove the filtration and/or had an extra sensor in the same optical path sample outlines in IR to determine z-depth, illuminating with a camera-mounted IR source, perhaps IR laser LEDs, and then apply that data as an alpha channel layer in real time in the camera? Any flat wall of any color could become a chromakey type wall, or no wall at all, you just need a foot or two difference in distance between the actor and anything else to select it for the z-depth. Not only that, but, if you extend this to a logical conclusion, you have a ONE-LENS LIVE 3-D TV CAMERA as well, if you can keep the various items in z-axis separated and tracked with their z-axis metadata. Is 10-bit enough to hold all that? Maybe? IR is not as sharp as visible wavelengths, so the key you cut using IR might be a little softer around the edges than a conventional chromakey. But I think edge detection and correction could be figured out by a clever coder.

I just want 1% of the gross for the idea.

“Oh, you wanted to RECORD that?”