Polyhedron edge mapping and infinity mirror discussion

[alandoak]

I built an icosahedron infinity mirror (I named him Wilson, after the volleyball in the movie Castaway), it has LED’s along all the inside edges, ~13" in diameter and 2-way mirrors on every face. I commonly mount him on a lantern pole and do roving art at music festivals for fun.

I also plan on constructing other shapes with straight edges and flat sides, not necessarily symmetric, not necessarily convex (stellated, for example), various sizes, various optics… imagine a sculpture garden of infinity mirrors, or a mobile with various infinity mirrors hanging from them…and I’m trying to think ahead on how I might systematically arrange the addresses (balanced against wiring symplicity) and 3D map them. And, thinking about what I could do with that mapping…

I took the following vid at Burning Man of someone’s dome, which gives me some ideas (no idea who made it or how).

If this is a solved problem, or someone wants to collaborate on a cool non-monetized art project, I’m open.

Also, any thoughts on considerations for LED choice, other than the common WS2812B? (WS2812B look good on Wilson, having experienced nothing else)
-I don’t see persistence of vision ever being desired.
-Wilson has 360 LED’s, some will be less, some will be 2x,3x or more.
-Some effects, like sound-reactive, sparse patterns and “soul capturing flashes” are great when bright… But many modes look best at really low brightness. With your face right up to it, high brightness can blow out the eyes and the volume develops a white glow from the scattering imperfections, which diminishes the black void effect. (huge strike against 12V addressable, which draw constant current even at low luminance), I’ve read the SK9822 (and the APA102 somewhat) have advantages at low brightness.
-Some designs will enjoy the aesthetics of skinny strips and/or higher densities (90,120,144 led/m).
-Cost is some consideration
-Redundancy is not a consideration, if an LED goes out, I’ll pop a panel and repair it
-4-pin is inconvenient, it means a ground strap/something with 3-pin MT30 or MT60 connectors (or dual connectors), and complicates node wiring and possible swivel design.
-Any favorite sources/brands for LED strips? I’m familiar with Amazon (BTF, Chinly, Alitove), Sparkfun and Adafruit (Adafruit seems expensive).

[wizard]

Very nice! I love the laser etched faces too.

Small world, I camped maybe a block away from that dome I remember reading something about it in the LEDs are Awesome facebook group, but I don’t have a link saved.

For 3D mapping, you could take the lines example, and compose that into your icosahedron. I don’t know the match off-hand, but I’m sure something could be written to programmatically generate icosahedrons of a given size.

APA102 and SK9822 have superior low brightness fidelity. Pixelblaze was designed to take advantage of that range (WS2812 support came later). They have the usual 8 bits of brightness per element like the WS2812, but also have an additional 5 bits (shared across RGB). It works out to effectively 13 bits worth of range. You don’t get the kind of posterization that happens to WS2812 at low light levels - the kind of thing where orange jumps to red as it runs out of low value bits. They have great color mixing at very low brightness levels, and can fade to black without a perceptible end.

I’d recommend you get a bit and try it out, it might just convince you it’s worth the extra wiring.

I sell LEDs in my Tindie store. Both SK9822 and RGBW SK6812 (the RGBW flavored WS2812s).

[wizard]

Thought of another idea if you keep WS2812s, there are lower current versions that will be dimmer, usually in the smaller packages.
Another way to do it would be to put a filter on the LEDs to darken them, you’d lose some max brightness, but would still have the same resolution just shifted darker.

[alandoak]

Thanks for the feedback.

BTW, not laser etched… for 5 sides: I used anti-glare acrylic that has the frosted look, applied exterior decals that I created on my Cameo 3 vinyl cutter, and applied interior 2-way window film (which allows a ghost of the opposing decal to be seen inside). It looks a lot like etched frosted glass.

The other 15 sides are regular acrylic 2-way mirrors. The frame is a $79 chandelier from Amazon, though future frames will be customizable to various geometries.

[Kylet]

That burning man led setup is probably a dmx controlled by resolume would be my guess. Not hard just time consuming and expensive.