From Zoom calls to SciFi effects films -- you can do it all with a DIY chromakey background made from retroreflective fabric, lit with a lens-mounted NeoPixel light ring. A QT Py microcontroller running CircuitPython allows you to control the light ring color and brightness with a push and twist of a rotary encoder knob.
Create chromakey mattes to place your subject in front of any background image or video you like using a retroreflective greenscreen/bluescreen -- you decide the color you need with the press of a knob.
Traditional greenscreen/bluescreen backgrounds are tricky to light evenly, and require a lot of space to prevent your subject from casting shadows and receiving green/blue spill. This retroreflective screen solves all of these problems -- and costs less, too!
This rig works equally well with realtime keyers (built into Zoom, OBS, and others) as well as offline compositing software, such as DaVinci Resolve or iMovie.
This technique is used in existing commercial systems, such as the Reflecmedia Chromatte/LiteRing and the LEDChromaKey system.
A friend of mine told me about this technique and said he'd built a DIY version that worked great. I figured NeoPixels would work well for this and my buddy gave me some spare retroreflective screen material to test it out. I did a quick test and found out that it works better than I'd hoped!
Elastic Band
You'll also need a single #33 size (approx. 3-1/2" x 1/8") rubber or silicone band. I like the silicone hair bands like these.
Retroreflective Fabric
Get a yard or two of retroreflective fabric in either 39" or 49" width. Available most readily on eBay, such as this item or this one
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