Notices by James Brown (ancientjames@mastodon.social), page 5

I have a habit of building displays that are just a confusing flickery mess on video.

It’s very unbalanced with only one collimator attached, so I’m spinning it too slowly for persistence of vision. But I’m sort of able to convince myself I’m seeing depth. There’s a lot of mechanical stuff I need to do before I can start cranking it up.

I had to turn the print 90 degrees - it wiggles rapidly doing the lens profiles, and when that was on the bed slinging axis it shook the whole room. It's a lot less dramatic when it's just moving the head.

The slat based collimators are such a pain, I've decided to go for it and try making lenses instead. I think a 3D printed mould will be good enough - the layer height is very much smaller than the LED size, and a bit of scattering is actually desirable. I'm printing this vertically so the lens profile gets the high resolution. It's going to be precarious when it reaches the top.

I think I can live with it. I printed it vase mode for speed, so I was expecting it to need a stiffer structure to hold it flat.

Bah.

I’ll chop the front off that, and stick it into this to make the mould.

I did have another swing at it. The first one I’d hoped to slip intact around a stiffer carrier. This one I made wider, and corrugated, so it printed better.

Following a series of poor decisions, I now have both a mould and a vacuum chamber coated in uncured silicone.

How can I be out of silicone?

I went back to the slats, and finally got all the bits hooked up together.

It sort of works?

Well I got a lens out of it in the end. It does make it more directional, but there’s more light off axis than I need.

The depth is smeared more than I want because the collimators are too shallow (because I don't like prints that take more than 16 hours to complete). I want to make them tighter, and spin the whole thing faster to compensate.

You can see what's going on a bit more clearly with a simpler shape. It looks better when you can use both eyes on it!

The nice thing about these LED panels is that they're very high framerate (and cheap!). I'm updating these at 1.5 KHz - with 3 of them in a ring, that's 4.5 KHz. Just driven in software from a (somewhat dizzy) Raspberry Pi.

That should contain or possibly create any shrapnel.

Just realised that I can increase the resolution by progressively offsetting each panel by 1/3 the LED pitch.

I'll probably make two displays now - finish off the autostereoscopic one, but then rearrange the geometry so that I can sweep through more than just a thickish-walled cylinder.

The thing I've been trying to make creates its 3D effect by displaying a whole different view in every direction, which means it can handle occlusion and fancy lighting at the cost of vertical parallax.

To turn that setup into a swept volume (where it's lighting up the LEDs according to where they are in space - full 3D, but glowy and transparent) I keep everything but the collimators, and just render each view with the near & far clip planes set really close together.

Making parts for this has been a real saga, so while I wait for a faster printer to arrive I tried removing the collimators and running it as a swept volume display. Now I’m thinking maybe that’s what I should have built in the first place.