Spinning 3D POV Display: a High School Term Project

If you are a fan of sci-fi shows you’ll be used to volumetric 3D displays as something that’s going to be really awesome at some distant point in the future. It’s been about forty years since a virtual 3D [Princess Leia] was projected to Star Wars fans from [R2D2]’s not-quite-a-belly-button, while in the real world it’s still a technology with some way to go. We’ve seen LED cubes, spinning arrays, and lasers projected onto spinning disks, but nothing yet to give us that Wow! signaling that the technology has truly arrived.

We are starting to see these displays move from the high-end research lab into the realm of hackers and makers though, and the project we have for you here is a fantastic example. [Balduin Dettling] has created a spinning LED display using multiple sticks of addressable LEDs mounted on a rotor, and driven by a Teensy 3.1. What makes this all the more remarkable is that he’s a secondary school student at a Gymnasium school in Germany (think British grammar school or American prep school).

volumetric-pov-display-built-by-high-schooler-led-boardsThere are 480 LEDs in his display, and he addresses them through TLC5927 shift registers. Synchronisation is provided by a Hall-effect sensor and magnet to detect the start of each rotation, and the Teensy adjusts its pixel rate based on that timing. He’s provided extremely comprehensive documentation with code and construction details in the GitHub repository, including a whitepaper in English worth digging into. He also posted the two videos we’ve given you below the break.

What were you building in High School? Did it involve circuit design, mechanical fabrication, firmware, and documentation? This is an impressive set of skills for such a young hacker, and the type of education we like to see available to those interested in a career in engineering.

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3D Printed Helix Displays Graphics in 3D

It looks like [Michel David] and his team at volumetrics.co have really upped their game: the game being production of a 3D volumetric video display.

We’ve covered an earlier version of the same technique, and still the best technical explanation of what they’re up to is to be found at their old website. But it’s a simple enough idea, and we expect that all of the difficulty is in making the details work out. But if you look at their latest video (just below the jump), we think that you’ll agree that they’ve ironed out most of the wrinkles.

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How a Real 3D Display Works

There’s a new display technique that’s making the blog rounds, and like anything that seems like its torn from [George Lucas]’ cutting room floor, it’s getting a lot of attention. It’s a device that can display voxels in midair, forming low-resolution three-dimensional patterns without any screen, any fog machine, or any reflective medium. It’s really the closest thing to the projectors in a holodeck we’ve seen yet, leading a few people to ask how it’s done.

This isn’t the first time we’ve seen something like this. A few years ago. a similar 3D display technology was demonstrated that used a green laser to display tens of thousands of voxels in a display medium. The same company used this technology to draw white voxels in air, without a smoke machine or anything else for the laser beam to reflect off of. We couldn’t grasp how this worked at the time, but with a little bit of research we can find the relevant documentation.

A system like this was first published in 2006, built upon earlier work that only displayed pixels on a 2D plane. The device worked by taking an infrared Nd:YAG laser, and focusing the beam to an extremely small point. At that point, the atmosphere heats up enough to turn into plasma and turns into a bright, if temporary, point of light. With the laser pulsing several hundred times a second, a picture can be built up with these small plasma bursts.

2-fig2

Moving a ball of plasma around in 2D space is rather easy; all you need are a few mirrors. To get a third dimension to projected 3D images, a lens mounted on a linear rail moves back and forth changing the focal length of the optics setup. It’s an extremely impressive optical setup, but simple enough to get the jist of.

Having a device that projects images with balls of plasma leads to another question: how safe is this thing? There’s no mention of how powerful the laser used in this device is, but in every picture of this projector, people are wearing goggles. In the videos – one is available below – there is something that is obviously missing once you notice it: sound. This projector is creating tiny balls of expanding air hundreds of times per second. We don’t know what it sounds like – or if you can hear it at all – but a constant buzz would limit its application as an advertising medium.

As with any state-of-the-art project where we kinda know how it works, there’s a good chance someone with experience in optics could put something like this together. A normal green laser pointer in a water medium would be much safer than an IR YAG laser, but other than that the door is wide open for a replication of this project.

Thanks [Sean] for sending this in.

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Volumetric display projects 200 Million voxels per second

Over the last four years, [Will] and [Gav] have spent their time creating a huge, high-resolution 3D display. The’re just about done with their build, so they decided to offer it up to the Internet in the hopes of people creating new 3D content for their display. They call their project the HoloDome, and it’s the highest resolution volumetric display we’ve ever seen.

The HoloDome operates by spinning a translucent helix around its vertical axis at 20 rotations per second. A pico projector above the helix capable of projecting 1440 frames per second (an amazing device by itself) displays 72 ‘z-axis’ frames for each of the 60 ‘x and y frames’ per second. The result is a 3D display with a 480 * 320 * 72 voxel resolution capable of displaying 20 frames per second.

This isn’t the first time we’ve seen a swept helix used as a volumetric display, but it is by far the highest resolution display of its type in recent memory. [Gav] and [Will] have put their HoloDome up on the Australian crowd-funded site Pozible if you’d like to buy your own, but thankfully the guys have included enough detail on the main site to reconstruct this project.

Check out the video after the break to see the HoloDome in action.

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