Hackaday Links: September 1, 2013


[Anton] has been doing some Commodore 64 Datasette experiments. He managed to connect the C64 audio traces to his smartphone and use it for tape playback.

Not wanting to actually disassemble his Mendel 3D printer, [SteveDC] figured out how to make extenders that increase his build height by about 40%.

We have fond memories of owning an 8088 PC. We did a lot of experimental programming on it but never anything as impressive as getting the TCP/IP stack to run on it. Then again, we’re not sure there was such a thing back when we owned the 10 MHz hardware. That’s right, the microcontrollers we mess around with now days are much faster than that old beast was.

When he goes running at night [Tall-drinks] straps a pico projector to his chest. We guess you’d call the readout a heads-up display… but it’s really more heads-down since it’s projecting on the pavement.

See how things heat up as a Raspberry Pi boots. This video was made using a thermal imaging camera to help diagnose a misbehaving board.

We don’t have very many trinkets on our desk (that would steal space normally reserved for clutter). But be would happily make room for this motorcycle model made from VCR parts (translated).

Dynamic bicycle headlight uses the open road as a display


This thing is so cool it almost looks fake. But [Matt Richardson] isn’t a hoaxster. He actually built what might be called a heads-down display for your bicycle. He refers to it as a headlight because it borrows a similar function. It mounts on the handlebars and shoots light off the front of the bike. But it’s more than just a battery and a bulb, this uses a pico-projector to give that light some meaning. In the video after the break he shows it off on the streets of NYC.

So far he’s only displaying information that has to do with the speed of travel, but the proof is there just waiting for a brilliant new use. Feeding the projector is a Raspberry Pi board. For this prototype [Matt] mounted it, along with the portable cellphone charger which plays the role of the power source, on a hunk of hardboard strapped inside the bike frame.

If you’re thinking of doing this one yourself beware of the BOM price tag. That projector he’s using runs upwards of $400. We wonder if you could hack together a rudimentary replacement with an old cellphone screen and this diy film projector?

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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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Update: using your forearms as a UI

This image should look familiar to regular readers. It’s a concept that [Chris Harrison] has been working on for a while, and this hardware upgrade uses equipment which which we’re all familiar.

The newest rendition, which is named the Omnitouch, uses a shoulder-mounted system for both input and output. The functionality is the same as his Skinput project, but the goal is achieved in a different way. That used an arm cuff to electrically sense when and where you were touching your arm or hand. This uses a depth camera to do the sensing. In both cases, a pico projector provides the interactive feedback.

There’s a couple of really neat things about this upgrade. First, it has a pretty accurate multitouch capability. Second, it allows more surfaces to be used than just your arm. In fact, it can track moving surfaces and adjust accordingly. This is shown in the clip after the break when a printed document is edited in real time. Pretty neat stuff!

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3D sphere display and controller

[Nirav] has been working on a spherical display for about a year now, and he just came up with a great way of interacting with this screen: an adjacent reality tracker that rotates the display to match the current orientation of the controller.

Earlier, [Nirav] built an 8-inch sphere display using a few 3D printed parts and a Showwx laser pico projector. The display looked great, but [Nirav] had no way to interact with it. To solve that problem, he put an inertial measurement unit inside a 3d printed model of the globe. The IMU communicates with a computer to read the rotation and orientation of [Nirav]‘s controller and adjust the spherical display accordingly.

It’s a very nice build that gets very close to futuristic sci-fi displays. At least now, [Nirav] can interact with the awesome satellite tracking app and continental drift simulation he created.

There’s a bunch of videos [Nirav] put up demoing what his display can do. You can check those out after the break.

via MAKE

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Projecting video directly onto the retina

With the head-mountable, augmented reality Google Glass capturing tons of attention in the press, it was only a matter of time before we saw a DIY retina projector. This isn’t a new build; [Nirav] has been working on it for a few months, but it might just be time for this information to be useful to someone.

A retina projector focuses laser light though beam splitters and concave mirrors to create a raster display on the back of your eye. There’s an incredible amount of research into this field, but not many DIY projects. To make this project a reality, [Nirav] picked up a SHOWWX laser video projector and mounted it in a 3D printed frame along with a few pieces of optical equipment.

[Nirav]‘s build isn’t without its drawbacks, though. The exit pupil, or the apparent size of the image, is only about 1.5 mm wide and much too small to be of any real use. Also, commercial retina projectors have an output of a puny 2 microwatts, where [Nirav]‘s laser projector puts out 200 millwatts. This is more than enough to permanently damage your eye.

Structured light 3d scanner

After futzing around with a cheap pico projector, a webcam and a little bit of software, [Jas Strong] built herself a 3d scanner.

In spite of the dozens of Kinect-based scanner projects, we’ve seen structured light 3d scanners before. This method of volumetric scanning projects a series of gradient images onto a subject. A camera captures images of the patterns of light and dark on the model, math happens, and 3d data is spit out of a computer.

[Jas] found a Microvision SHOWWX laser pico projector on Woot. The laser in the projector plays a large part in the quality of her 3d models – without a focus, [Jas] can get very accurate depth information up close. A Logitech webcam modified for a tighter focus handles the video capture responsibilities. The software side of things are a few of these structured light utilities that [Jas] melded into a single Processing sketch.

The results are pretty remarkable for a rig that uses woodworking clamps to hold everything together. [Jas]‘ 3d model of her cat’s house looks very good. She’s got a few bugs to work out in her setup, but [Jas] plans on releasing her work out into the wild very soon. We’ll update this post whenever that happens. made her code available here. The code requires the ControlP5 and PeasyCam libraries.