@ancientjames@mastodon.social

James Brown @ancientjames@mastodon.social

· 2w ago

Replying to

So much of the edit was spent grappling with crappy footage and trying to decide whether I should reshoot everything or simply disappear into the woods never to be seen again, so it's gratifying to see youtube comments saying the perfect camera work proves it's all fake.

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James Brown @ancientjames@mastodon.social

· 1mo ago

Boosted by @trending@homestead.social

The usual apologies for resolution, colour depth, sync and so forth. But I tried raytracing a glass sphere to show the light field doing its thing.

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James Brown @ancientjames@mastodon.social

· 2mo ago

Boosted by @GroupNebula563@mastodon.social

I always complain about how hard it is to do justice to my 3D displays in 2D video, but this one really takes it to new levels. I think I've managed something here which gives a sense of what you see irl. The trick is to film it in potato vision - in high resolution 2D you only see the underlying pixel grids.

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James Brown @ancientjames@mastodon.social

· 2mo ago

Replying to

The video is here! https://www.youtube.com/watch?v=41b8fw3_wP8 The build files are here! https://github.com/AncientJames/Scanwheel/

Scanwheel, a miniature mechanical TV

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James Brown @ancientjames@mastodon.social

· 2mo ago

Found it! The one image I have of my first mechanical tv.

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James Brown @ancientjames@mastodon.social

· 8mo ago

Boosted by @wtrmt@mastodon.social

"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

Digital Iris

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James Brown @ancientjames@mastodon.social

· 3mo ago

Replying to

You know the rules.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Boosted by @ferrix@mastodon.online

Here's another Janky Display Device Build Video https://makertube.net/w/3cNvxH4xNjdnn2z7TYS8xP (Also available with adverts, if you want to feed the algorithm and to a certain extent me: https://youtu.be/YbxsYhTjYFI )

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

Now you may say, James, did you know that faster computers exist? But I like embedding a cheap SBC. When I abandon this project and move on to something else, I want it frozen in a state that Just Works. I don't want to turn it on a year from now only to wait 30 minutes while it enshittifies itself.

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James Brown @ancientjames@mastodon.social

· 6mo ago

Ever since I put this Raspberry Pi in a sweet all metal heatsink case, the wifi reception has been... oh.

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James Brown @ancientjames@mastodon.social

· 6mo ago

I bought this fiddle toy to pad out an aliexpress order, and it’s crying out to be turned into a functioning keyboard but I’m not sure what the gimmick would be.

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James Brown @ancientjames@mastodon.social

· 6mo ago

Lovely morning in Wellington, if you're above 250m.

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James Brown @ancientjames@mastodon.social

· 7mo ago

Breaking out the swivelcam again.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

And here's the correct version of that video, without the horrible jump. https://www.youtube.com/watch?v=cK78WLYWNAs

Multiview Stereo Fog Projection

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James Brown @ancientjames@mastodon.social

· 6mo ago

I bought some cheap "Mitutoyo" calipers from AliExpress, and they're really good. The effort they put into making them convincing paid off. Would recommend.

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James Brown @ancientjames@mastodon.social

· 5mo ago

People watch my videos and think, well this guy's clearly an idiot.

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James Brown @ancientjames@mastodon.social

· 9mo ago

Boosted by @ferrix@mastodon.online

Replying to on mastodon.social

It’s such a good idea putting a wildlife sanctuary in a city. You read about an island being declared rat free, and that’s good, but I never saw the rats and I’ll never notice the wildlife, so it doesn’t really hit home. But here, there’s no missing the fact that year by year the sounds around the house become richer and wilder.

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James Brown @ancientjames@mastodon.social

· 2mo ago

Replying to

@RueNahcMohr@infosec.exchange Yes - there's an OpenSCAD model that lets you dial whatever parameters you want, including interlacing.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@commanderred@chaos.social It's scanning a drum very fast in front of a high refresh rate led panel. The drum has pinholes arranged in it such that the whole screen gets exposed once per revolution, but at any instant in time there are only a few pinholes in front of the screen. The trick is generate an image on the screen, synchronised with the rotation, which shows the views through the pinholes. The result is that all the light rays of a 3D scene are sent out in all the correct directions.

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James Brown @ancientjames@mastodon.social

· 47mo ago

I was asked about selling the computer bricks in kit form, and gave the same answer I've given before - that the assembly process is really fiddly, requires materials that most people don't have at hand, and is very challenging to get right on the first attempt.
But what if I made just the circuitry available as a kit? Would anybody be interested in this as an object in its own right? It clips on to Lego studs & has two capacitive touch buttons, a 72x40 screen, and an RP2040 stuffed inside it.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@jasoncoon@leds.social Thank you! As usual it's been a massive saga getting useable video of it in action. I don't know why I do this to myself.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@orangutanlibrarian@mastodon.au @uint8_t@chaos.social The round mirrors are sold on AliExpress as "wedding coasters"

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@MLE_online@social.afront.org If I don't squash the roll into an oval, it always quietly unspools itself.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@dvandal@infosec.exchange I don't know if you've seen the display I made based on that - https://mastodon.social/@ancientjames/115578423742426811 Spinning the block would allow a higher density, but alignment would be very challenging.

mastodon.social

James Brown: "It's fun discovering what sort of content works b…" - Mastodon

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James Brown @ancientjames@mastodon.social

· 10mo ago

Replying to

@ferrix@mastodon.online @RonJeffries@mastodon.social

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@foerterer@mastoart.social Ah, it's way lower resolution than you give it credit for. It's 48 holes; 48 scanlines. The horizontal resolution is 80 - that's how many times it can refresh the panel during the time it takes one hole to travel all the way across it. 10,000 fps on the panel, 30 fps on the drum, and the visible section is 1/4 of a turn; 10000/30/4 ~ 80. Looked at another way, in a single frame, it can put an image behind a hole at each of 48 rows by 80 cols; 3840 pixels, not lines (albeit 3D pixels).

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

It's worth adding that the scanned resolution is independent of the resolution of the LED panel. The approach is essentially the same as a mechanical TV, where the disk (or drum) is scanning in front of a single light source. The resolution is limited by the number of holes vertically, and how many times it can change the light intensity during the horizontal sweep of the hole. (As it turns out, here the scanned resolution is 80x48, basically the same as the panel's 64x64)

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

The other neat thing about this compared to a 2D mechanical TV is that the view window is much larger. With a single light source there can be only one hole illuminated at a time, so with 36 lines you can only have a window 10 degrees across. This doesn't have that restriction - it can have multiple holes in front of the panel simultaneously as long as it's rendering a separate view to each hole's local region. In fact, the plan is to add more panels and make it fully 360.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@foerterer@mastoart.social @commanderred@chaos.social It's ordered - hexagonal packing to maximise the distance between neighbours (& therefore view angle), in a helix so that each hole is at a different vertical height (to scan the whole region).

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@commanderred@chaos.social (and the glib answer to 'how does it render that many frames per second' is that the frames are very small)

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@foerterer@mastoart.social The trick with multiple holes is to split up the generated image on the screen to make multiple projectors, so it doesn't have to do it one at a time (by trading off some of the resolution of the panel). If you were to watch the screen in slow motion, you would see little fish-eye regions scrolling past in sync with the holes in the drum. (and in fact you can sort of see that at the end of this video https://mastodon.social/@ancientjames/116338945925889785 )

mastodon.social

James Brown: "I finally wrote the code for this, and it basical…" - Mastodon

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@foerterer@mastoart.social It might be easier to visualise by imagining there is only one hole, and it's being scanned in front of the screen like a crt raster. Wherever it is at any instant, there is a unique image being generated on the screen behind it. That image is shining out through the pinhole, as though it's the lens of a projector. The result is as if there are thousands of projectors in a grid, making up the image. Each one looks different depending on where your eye is, which is why it's 3D.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@foerterer@mastoart.social random displacements wouldn't help here - the holes have to be evenly spaced vertically because that's where the scan lines come from, and they have to be maximally separated horizontally because the closer they are the smaller the addressable region behind them is, and the smaller the angle of view. If you jitter the holes vertically you get overlapping and gappy scanlines, and if you jitter them horizontally, other than the view thing, it just slightly changes the timing.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@foerterer@mastoart.social The hole positions are unrelated to the layout of the LEDs on the panel behind. The trick that makes this thing work is that the holes are a few centimetres in front of the panel. What you see through the hole - the specific LED that's visible - is entirely view dependent, which is why each eye sees a different scene and why it's 3D. Only rarely will your eye align exactly with an LED. Most of the time it's somewhere between them. When I spoke about scanlines, it was the drum's scan.

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James Brown @ancientjames@mastodon.social

· 5mo ago

Replying to

@PatHightree@mastodon.gamedev.place I can change the swivel cam geometry a little by rearranging bits of aluminium extrusion.

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