Nostr notes by James Brown

"Animated Bokeh" has been on my whiteboard for a long ...

2026-02-07T17:32:23Z

"Animated Bokeh" has been on my whiteboard for a long time, and this is the result.

I thought it would just be for cheesy novelty effects, but it also does lightfield manipulation that was cooler than I expected.

https://www.youtube.com/watch?v=Kg_2MAgS_pE

It's fun discovering what sort of content works best on these ...

2025-11-19T21:13:08Z

In reply to nevent1q…ppul
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It's fun discovering what sort of content works best on these displays. With the spinning LEDs it was wireframe spaceships. This thing is all about museum quality loot.

Incidentally, the viewport version of that animation doesn't ...

2025-11-15T01:09:26Z

In reply to nevent1q…pn8q
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Incidentally, the viewport version of that animation doesn't work - the points only line up when refraction is taken into account.
I've used the equation for refraction countless times in shaders, but somehow it kind of blows my mind that it actually works IRL.

I rendered off an animation showing how the points are aligned ...

2025-11-15T00:58:27Z

In reply to nevent1q…y0pk
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I rendered off an animation showing how the points are aligned when seen from exactly the right spot.

I learned my lesson from the previous displays, and this time ...

2025-11-14T06:30:30Z

In reply to nevent1q…syfa
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I learned my lesson from the previous displays, and this time wrote the simulator before writing the actual driver code.
It allowed me to quickly catch a flipped axis which I can believe would have otherwise taken me days to figure out.

Latest voxels! Flickery when filmed ✓ Distracting reflections ...

2025-11-14T03:04:26Z

Latest voxels!

Flickery when filmed ✓
Distracting reflections ✓
You kind of have to be there ✓

I lost all my pre-2013 photos in a hard drive failure some years ...

2025-09-17T06:26:57Z

I lost all my pre-2013 photos in a hard drive failure some years ago (irreplaceable baby pics etc), and chalked it up as a lesson to always make backups. But I just spent three days clearing out the garage for some work to be done, and it turns out the *actual* lesson is to always remember that you did make a backup you idiot, it's in the garage under a pile of crap.

I think I'm ready to call this piece finished. ...

2025-08-01T02:31:31Z

I think I'm ready to call this piece finished.

I made a new mouth mechanism. I'm calling it ...

2025-07-24T03:20:20Z

I made a new mouth mechanism. I'm calling it Selectramatronics.

I have this little jog/shuttle dial which would be great but for ...

2025-07-14T22:33:58Z

I have this little jog/shuttle dial which would be great but for one flaw - the jog wheel doesn't generate an event for the first click when it changes direction. If you go 3 clicks forward then 3 clicks back, it outputs 3 forwards and 2 back. It doesn't end up back where it started.
I popped it open to see what's going on, and the encoder is behaving sensibly - it seems to just be a firmware issue. So do I try to reflash that MCU, chisel it off and cram a Pico in there, or make a whole new PCB?

I unsubscribed from a podcast because the hosts were a bit dull ...

2025-06-18T04:37:31Z

I unsubscribed from a podcast because the hosts were a bit dull and frankly sounded drunk. I was some way through listening to an interview with someone I usually like and thinking, this guy sounds drunk and a bit dull, when I realised the playback speed was still set to 75% from watching an XKCD video earlier.

I clambered down onto the rocks to get a better look at this eel, ...

2025-05-30T01:56:34Z

I clambered down onto the rocks to get a better look at this eel, and it heaved itself up onto them to get a better look at me.

I wrote a program to lipsync the shipping forecast in a terminal ...

2025-05-25T06:19:05Z

I wrote a program to lipsync the shipping forecast in a terminal window, and I have no regrets.

Very grateful to past me for open sourcing one of my projects, ...

2025-05-06T03:33:38Z

Very grateful to past me for open sourcing one of my projects, because I just needed to build a new version and it would have been a real pain to work out how to do that again from scratch.

My superpower is getting out of sync with the record button on my ...

2025-04-25T00:01:20Z

My superpower is getting out of sync with the record button on my camera, and ending up with lots of footage of me faffing around and muttering to myself, cutting out as soon as something interesting is about to happen.

I plugged this in for a soak test a week ago and forgot about it, ...

2025-04-20T09:13:53Z

I plugged this in for a soak test a week ago and forgot about it, so I guess it's soaked.

The UI is randomly generated, and I love what it came up with here.

Nostr event nevent1qqs9gs9539r6yr5sjgktn0nqjy5rr2phjwedkm0zlm7g5rezg73pfrszyzg2e0dtxjq6qstrlf4p9k2rfe0pzynsvlvkp2k8t4hutaasnd5pshkwpnu

2025-02-28T02:50:51Z

There's now a making-of video for this display. ...

2025-02-27T06:56:58Z

In reply to nevent1q…nq5h
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There's now a making-of video for this display. https://www.youtube.com/watch?v=zz59e1wWyVc

I have Kiwix and an offline copy of wikipedia on my phone, and my ...

2025-02-27T03:18:36Z

I have Kiwix and an offline copy of wikipedia on my phone, and my local Gen Z was so surprised and excited by the concept that I thought we should have a dedicated thing for it. Cheap e-reader plus 128GB SD card plus no wifi.

One problem with a 360° display is that sometimes you want the ...

2025-02-21T08:00:38Z

One problem with a 360° display is that sometimes you want the content to align with the controller.
This nifty hack uses the fact that everything is spinning, including the bluetooth antenna. It creates a map of the signal strength to any connected controllers and points to where it's strongest.

Seems you can’t do a picture and a poll at the same time. But ...

2025-01-21T03:53:49Z

Seems you can’t do a picture and a poll at the same time. But does this battery look spicy to you?

Exclusive behind the scenes footage of my high end motion control ...

2024-12-23T04:07:31Z

Exclusive behind the scenes footage of my high end motion control system.

Now with explosions https://www.youtube.com/watch?v=ILNbnWneTIg

2024-12-20T02:21:12Z

In reply to nevent1q…zlm0
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Now with explosions https://www.youtube.com/watch?v=ILNbnWneTIg

Amazing what these Arm processors can do. ...

2024-12-16T08:10:00Z

In reply to nevent1q…gsu4
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Amazing what these Arm processors can do.

Everyone needs to build one of these displays so I can spend my ...

2024-12-15T09:41:09Z

In reply to nevent1q…f3eq
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Everyone needs to build one of these displays so I can spend my time writing games for it.

I tried the thumbnail testing feature on Youtube for the first ...

2024-12-10T22:38:53Z

In reply to nevent1q…jc6l
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I tried the thumbnail testing feature on Youtube for the first time, which was fun. Upload 3 different images, and it randomly applies them and shows you which one was the most engaging. This was the winner.

(I didn't include one with my surprised face and an overlaid arrow pointing at something)

Construction video for this display… ...

2024-12-09T18:31:25Z

In reply to nevent1q…jshr
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Construction video for this display… https://youtu.be/pcAEqbYwixU

I built a contraption for my camera ...

2024-12-04T21:14:37Z

In reply to nevent1q…fg7d
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I built a contraption for my camera

You look like a good Joe ...

2024-11-27T04:46:04Z

In reply to nevent1q…u20z
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You look like a good Joe

What this thing needed was another source of barely recognisable ...

2024-11-24T04:46:06Z

In reply to nevent1q…aecg
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What this thing needed was another source of barely recognisable low res flickery points of light.

https://www.youtube.com/watch?v=ydk3BhlUWYE I've been working ...

2024-11-22T22:42:24Z

In reply to nevent1q…6jgm
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https://www.youtube.com/watch?v=ydk3BhlUWYE I've been working more on capturing footage. Hand held camera movement is still a mess, but putting the content into rotisserie mode helps sell the 3D with a static camera.

Happy birthday to Olive, 20 years old today. ...

2024-11-20T19:39:30Z

Happy birthday to Olive, 20 years old today.

Yet another round of finding new places to hang counterweights, ...

2024-11-14T04:09:16Z

In reply to nevent1q…ygv9
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Yet another round of finding new places to hang counterweights, and I’ve hit 900rpm - 30fps. Amazing to scroll back to the start of this thread and see me wonder if I could get some sort of rudimentary depth effect going.

Go spudsters ...

2024-11-01T07:01:58Z

Go spudsters

Meme crustacean ...

2024-10-28T05:16:20Z

In reply to nevent1q…p0j5
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Meme crustacean

Easier to see the 3D when it's only the camera that's ...

2024-10-26T06:53:14Z

In reply to nevent1q…qwuj
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Easier to see the 3D when it's only the camera that's moving.

Now thinking I should have filmed the tool I made to press all ...

2024-10-19T00:54:14Z

In reply to nevent1q…dr46
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Now thinking I should have filmed the tool I made to press all the clips on this IEC socket so I could get it out of the housing in order to film the satisfying click it makes when it goes in.

Taking it all apart so I can film myself making it. ...

2024-10-19T00:33:02Z

In reply to nevent1q…x28a
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Taking it all apart so I can film myself making it.

25 fps. That's an actual frame rate. ...

2024-10-11T23:15:44Z

In reply to nevent1q…laa3
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25 fps. That's an actual frame rate.

Nostr event nevent1qqsz4n2mjsq0a4a6ltc54gs3lvvxwc7c38y9tw8vyzpx5xdu34e88aqzyzg2e0dtxjq6qstrlf4p9k2rfe0pzynsvlvkp2k8t4hutaasnd5psx4d2nm

2024-09-27T22:09:25Z

In reply to nevent1q…nhpq
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Enbubbled.

With the previous dome the cut had a somewhat hand made look to ...

2024-09-21T02:00:21Z

In reply to nevent1q…gjzs
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With the previous dome the cut had a somewhat hand made look to it, so I printed a thin piece of trim to slip over the edge and keep it neat. It was too big for the printer so I used TPU, printing it in a spiral and flexing it back in to the right diameter. An unexpected benefit was that it was way quieter with that isolating the dome from the base.
This time the cut went better, but I’m still going to give it a gasket for that reason.

There’s a fair bit of planning involved in finding the true ...

2024-09-20T23:56:24Z

In reply to nevent1q…h3dd
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There’s a fair bit of planning involved in finding the true centre and height of these domes. When I come to make the cut it feels like cleaving the Cullinan diamond.

Original voxels ...

2024-09-17T08:45:14Z

In reply to nevent1q…al8p
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Original voxels

2D video of 3D projection of 4D object. ...

2024-09-15T04:04:38Z

In reply to nevent1q…jy6j
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2D video of 3D projection of 4D object.

There’s now an accelerometer in the base, synced to the ...

2024-09-14T05:22:19Z

In reply to nevent1q…mf3l
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There’s now an accelerometer in the base, synced to the rotation of the screen. I’m hoping this will help me get it balanced better. I don’t entirely understand the shape it’s producing, but the line is pointing in roughly the direction I think it should be pointing.

New dome! There are many advantages to moving to smaller panels ...

2024-09-08T22:22:56Z

In reply to nevent1q…z0sy
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New dome!
There are many advantages to moving to smaller panels in the new design (momentum etc), but the price drop going to a 300mm dome from 400mm would be justification enough.

So many complaints about the framerate on that last video, so I ...

2024-09-07T00:09:57Z

In reply to nevent1q…7f6v
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So many complaints about the framerate on that last video, so I decided to upload one with a shorter exposure and more flicker. But I still ended up keeping it below 30 fps, so I suspect the complaints will be about both framerate and flicker. Just have to hope the algorithm doesn’t go so large on this one. https://youtu.be/gBfclb9hXCI

Oh I meant more in the sense of "I should get off my arse and ...

2024-09-05T08:43:18Z

In reply to nevent1q…amg5
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Oh I meant more in the sense of "I should get off my arse and do it". I'm familiar enough with the mechanics of it.

I’d like an archive of the gadgets I’ve made over the years; ...

2024-09-05T05:26:28Z

In reply to nevent1q…x07y
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I’d like an archive of the gadgets I’ve made over the years; pictures, videos, descriptions sort of thing.

Nostr event nevent1qqsrxej8m3c23xtdr6eluk64ytzqhasfakmm9uqlusx9hwune7mm90szyzg2e0dtxjq6qstrlf4p9k2rfe0pzynsvlvkp2k8t4hutaasnd5psy53zat

2024-09-04T22:46:29Z

I really need to make a website.

In motion https://youtu.be/na7pvihXhYs

2024-09-01T00:19:35Z

In reply to nevent1q…9p7m
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In motion https://youtu.be/na7pvihXhYs

This is not a good VR camera. ...

2024-08-30T23:12:25Z

This is not a good VR camera.

These guys. ...

2024-08-30T08:13:24Z

In reply to nevent1q…ajav
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These guys.

Dynamic balancing using a tray of marbles and iPhone slowmo. ...

2024-08-30T00:52:52Z

In reply to nevent1q…qa7c
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Dynamic balancing using a tray of marbles and iPhone slowmo.

First test of the new design, and already I’m happy. Quiet, ...

2024-08-26T09:11:58Z

In reply to nevent1q…8vyg
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First test of the new design, and already I’m happy. Quiet, high refresh rate, and doesn’t feel like it’s seconds away from embedding itself in my face.

Maybe it would be useful in a high radiation environment idk ...

2024-07-14T05:30:45Z

In reply to nevent1q…a38n
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Maybe it would be useful in a high radiation environment idk

Why did I do this? ...

2024-07-12T09:01:29Z

In reply to nevent1q…feky
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Why did I do this?

I encapsulated the ends without breaking too many. Now I just ...

2024-07-06T07:22:47Z

In reply to nevent1q…ur0z
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I encapsulated the ends without breaking too many. Now I just need to pixel map them.

Nothing like Kapton tape to make you feel like you're doing ...

2024-07-06T07:16:30Z

In reply to nevent1q…09nq
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Nothing like Kapton tape to make you feel like you're doing Technology.

I’ll have to rethread it and put the 14 extra around the edge. ...

2024-06-30T06:16:38Z

In reply to nevent1q…k23l
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I’ll have to rethread it and put the 14 extra around the edge.

I guessed 512 or under, annoyingly.

2024-06-30T06:08:36Z

In reply to nevent1q…czvm
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I guessed 512 or under, annoyingly.

526. There are 526 individual strands. ...

2024-06-30T06:07:47Z

In reply to nevent1q…p2de
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526. There are 526 individual strands.

Have you ever wondered how many strands are in one of these tat ...

2024-06-30T06:06:40Z

Have you ever wondered how many strands are in one of these tat shop fibre optic wands?

In practice it's complicated by the fact that these panels ...

2024-06-11T08:31:05Z

In reply to nevent1q…x90h
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In practice it's complicated by the fact that these panels update two lines at once. Every time you update a column in the outer half, you're also updating one in the inner half. I couldn't find a simple procedural update strategy to spread these evenly, so I ended up generating a lookup table for it using simulated annealing.

The real improvement comes when you adjust the update rate for ...

2024-06-11T08:30:39Z

In reply to nevent1q…944z
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The real improvement comes when you adjust the update rate for each column to match the length of the track they have to sweep out. Instead of wrapping around when you reach the last column, you wrap around when your counter reaches the square of the number of columns, and you update the column corresponding to the integer square root of the counter. This gets rid of the bright dense region in the middle, and adds more updates out at the edges making them less sparse.

If you turn the panels 90 degrees so their scan lines are now ...

2024-06-11T08:30:12Z

In reply to nevent1q…24xv
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If you turn the panels 90 degrees so their scan lines are now columns, you can do a bit better. The update doesn't have to be sequential - instead of stepping one column at a time, you can skip a few each time. As long as you pick a number which is coprime with the number of columns, and you wrap around once you go past the last one, you'll still visit each of them but spread out more evenly throughout the volume.

This display works by spinning a matrix display rapidly about a ...

2024-06-11T08:29:40Z

In reply to nevent1q…mt4a
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This display works by spinning a matrix display rapidly about a vertical axis, lighting up each LED as it passes through part of a 3D image. The way you update the displays has a big impact on the quality of the image.
In this gif, each dot represents a column of LEDs - we're looking at the device from above. Here the panel is treated like a 2D display which just happens to be moving. Each scan line is repeatedly visited in turn, sweeping out a set of slices where the image can be displayed.

Doom running at a larger scale. Easier to make out what's ...

2024-04-27T08:40:12Z

In reply to nevent1q…wh66
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Doom running at a larger scale. Easier to make out what's going on, harder to see what's shooting at you.
https://youtu.be/bRe1OSkeiQg

I do like an ample window and natural light, but it makes it hard ...

2024-04-27T07:24:48Z

In reply to nevent1q…wu9w
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I do like an ample window and natural light, but it makes it hard to see the leds. Hence this pirate astronaut.

Monsters. https://youtu.be/yIfgjr-B8xI

2024-04-27T06:50:27Z

In reply to nevent1q…82w0
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Monsters.
https://youtu.be/yIfgjr-B8xI

kind of feels like it needs monsters? ...

2024-04-21T08:37:23Z

In reply to nevent1q…tgn0
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kind of feels like it needs monsters?

I’m now suspicious of all the PLA parts. The little pit with ...

2024-04-01T05:05:59Z

In reply to nevent1q…6cwf
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I’m now suspicious of all the PLA parts. The little pit with the Pi in it is getting very warm.

This feels like a good match of style and content. ...

2024-03-31T06:59:45Z

In reply to nevent1q…xah8
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This feels like a good match of style and content.

I continue to fail to shoot footage of it that does it justice. ...

2024-03-31T02:57:49Z

In reply to nevent1q…l4nr
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I continue to fail to shoot footage of it that does it justice.

Pi 4 model A ...

2024-03-31T02:39:26Z

In reply to nevent1q…7wgm
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Pi 4 model A

That's the mount for the slip ring. A cylinder carrying a ...

2024-03-31T02:07:27Z

In reply to nevent1q…y3mw
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That's the mount for the slip ring. A cylinder carrying a couple of copper bands fits over the pillar, and an M4 bolt goes own the middle to hold it all together. It has very clearly become bent, and without any signs of cracking. Presumably, as it spins, it heats up enough to soften the PLA, and the spring loaded brushes push it out of alignment.

I've reprinted it in ABS; going to see how well that lasts.

It feels as though I'm endlessly rebuilding it, for ...

2024-03-31T02:03:34Z

In reply to nevent1q…hn6w
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It feels as though I'm endlessly rebuilding it, for diminishing improvements. But in the most recent rebuild I finally solved a mystery that has been bugging me. When the display had been running for a while, it would quite abruptly lose balance and start vibrating. After the last occurrence, it was never quite the same. On stripping it down I found this.

In the continuing quest for higher rpm, I've moved the ...

2024-03-31T01:57:02Z

In reply to nevent1q…nwll
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In the continuing quest for higher rpm, I've moved the controller down below the screen and across the axis of rotation. It's a lot harder to get at if I need to rewire anything, but it does improve the balance.

I mean, you should have seen it before. ...

2024-02-18T07:48:00Z

In reply to nevent1q…jszr
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I mean, you should have seen it before.

I rewired the back of the panel to tidy up all the loose flappy ...

2024-02-18T07:38:28Z

In reply to nevent1q…m27t
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I rewired the back of the panel to tidy up all the loose flappy cables. It now manages 600 rpm, which is not too flickery.

yes, and frosted privacy films. What I really want is a coating ...

2024-02-18T01:46:33Z

In reply to nevent1q…7lez
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yes, and frosted privacy films. What I really want is a coating that will form little beads on each LED.

They really need to be diffused at the point where they're ...

2024-02-17T01:25:44Z

In reply to nevent1q…aguv
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They really need to be diffused at the point where they're emitted, which would also help a little with the dimming along the direction of view. I haven't yet come up with a good approach for that.

There must be at least 6D here. ...

2024-02-16T07:21:53Z

In reply to nevent1q…ma6s
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There must be at least 6D here.

Guess I’m doing a cone next. ...

2024-02-16T04:19:45Z

In reply to nevent1q…84wm
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Guess I’m doing a cone next.

Shiny! (Maybe too shiny. ) ...

2024-02-16T02:38:41Z

In reply to nevent1q…3vn5
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Shiny! (Maybe too shiny. )

It's a nice fluid motion on the panel, but overall it ...

2024-01-22T04:37:09Z

In reply to nevent1q…ylmj
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It's a nice fluid motion on the panel, but overall it doesn't bring me joy.

I had a panel left over, and I thought I should have another stab ...

2024-01-22T04:15:08Z

In reply to nevent1q…dgrp
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I had a panel left over, and I thought I should have another stab at an oscillating display. I wanted to give it an undulating motion and came up with what seemed like a nice linkage, but the end result looks like it was designed by Trevithick.

Latest flickery mess ...

2024-01-22T04:10:28Z

In reply to nevent1q…3392
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Latest flickery mess

Incidentally, those models are from Cheello's voxel Doom: ...

2024-01-05T05:54:44Z

In reply to nevent1q…h8m3
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Incidentally, those models are from Cheello's voxel Doom: https://www.moddb.com/mods/doom-voxel-project/addons/voxel-doom - It's a lovely mod, and makes Doom feel more like my memories of playing it than the real thing does.

The other problem I have is that to sell the 3D effect I need to ...

2024-01-05T05:50:40Z

In reply to nevent1q…5ada
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The other problem I have is that to sell the 3D effect I need to move the camera around a lot, so I'm going to have to put some effort into building a studio backdrop.

Slightly higher rpm, slightly longer shutter. ...

2024-01-05T05:48:13Z

In reply to nevent1q…3pg2
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Slightly higher rpm, slightly longer shutter.

My target for this display is 600 rpm - lower than that and ...

2024-01-05T04:46:16Z

In reply to nevent1q…xqfg
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My target for this display is 600 rpm - lower than that and it's too flickery; higher than that and I can't refresh fast enough to get 400 voxels around the circumference without dropping to 1 bpc. I'm nudging 400 rpm here, and it's still pretty unfilmable and absolutely terrifying to be close to. I have to decide whether the overall approach is worthwhile enough to start spending money on aluminium and polycarbonate.

I've implemented parts of a content pipeline for rendering a ...

2024-01-02T04:44:20Z

In reply to nevent1q…a7xw
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I've implemented parts of a content pipeline for rendering a scene on the PC and streaming it to this display, but writing video streaming code is so much less fun than playing with voxels that it may take a while to finish.
Here, I've stored the animation uncompressed on the display itself, and am updating it as fast as the Pi's SD card can handle. (Not very fast.)

I am having so much fun with this thing. ...

2023-12-30T03:44:58Z

In reply to nevent1q…ctyw
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I am having so much fun with this thing.

Help me Obi-Wan Clownobi ...

2023-12-29T06:47:35Z

In reply to nevent1q…4tx8
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Help me Obi-Wan Clownobi

I really need to get a hobby where missing my framerate target ...

2023-12-29T00:01:49Z

In reply to nevent1q…40zd
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I really need to get a hobby where missing my framerate target doesn't make me physically nauseous.

Trademark flickery mess ...

2023-12-28T07:39:40Z

In reply to nevent1q…a9lw
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Trademark flickery mess

It would be convenient to address the voxel data as a stack of ...

2023-12-27T23:17:23Z

In reply to nevent1q…0ss3
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It would be convenient to address the voxel data as a stack of horizontal slices, because that's how it's exported from lots of existing tools. I have to rotate it 90 degrees though, because scanning out is faster if each column's data can be addressed as consecutive bytes.
It's a small change, but there's a 6.5x difference in speed between the two orientations, which directly translates into voxel density in the final output.

Slowly turning up the dial at arm’s length. ...

2023-12-27T01:51:48Z

In reply to nevent1q…3uyc
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Slowly turning up the dial at arm’s length.

I massively overestimated how much lead would be needed to ...

2023-12-22T06:36:06Z

In reply to nevent1q…t640
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I massively overestimated how much lead would be needed to counterbalance the small amount of slightly off-axis electronics.