Want Gesture-Tracking? All You Have To Do Is Lift Your Finger.

Watching Tony Stark wave his hands to manipulate projected constructs is an ever-approaching reality — at least in terms of gesture-tracking. Lift — a prototype built by a team from UC Irvine and FX Palo Alto Laboratory — is able to track up to ten fingers with 1.7 mm accuracy!

Lift’s gesture-tracking is achieved by using a DLP projector, two Arduino MKR1000s, and a light sensor for each digit. Lift’s design allows it to work on virtually any flat surface; the projected image acts as a grid and work area for the user. As their fingers move across the projected surface, the light sensors feed the information from the image to the Arduinos, which infers the location of each finger and translate it into a digital workspace. Sensors may also be mounted on other objects to add functionality.

So far, the team has used Lift as an input device for drawing, as well as using it to feign gesture controls on a standard laptop screen. The next step would be two or more projectors which would allow Lift to function fully and efficiently in three dimensions and directly interacting with projected media content. Can it also operate wirelessly? Yes. Yes, it can.

While we don’t have Tony Stark’s hologram workstation quite yet, we can still play Tetris, fly drones, and mess around with surgical robots.

Get Subpixel Printing With a DLP 3D Printer

A DLP 3D printer works by shining light into a vat of photosensitive polymer using a Digital Light Processing projector, curing a thin layer of the goo until a solid part has been built up. Generally, the resolution of the print is determined by the resolution of the projector, and by the composition of the polymer itself. But, a technique posted by Autodesk for their Ember DLP 3D Printer could allow you to essentially anti-alias your print, further increasing the effective resolution.

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This DLP 3D Printer Build Is Going Really Well

We suppose [Dan Beaven] got up one day and said, “I’ll make my own resin 3D printer, with resin management and an advanced separation mechanism!” It’s a build log that shows just how possible it is to roll your own resin printer.

Prints on a dime!
Prints on a dime!

The machine isn’t finished yet, but the example prints coming off it are already very impressive. [Dan] stopped the print midway to get this photo of the detail on the stairs in the standard rook torture test.

[Dan] wants a lot of features from his machine that some of the more polished commercial printers are only now offering. One really nice one is the sliding and twist separation instead of tilt. This will allow for cleaner separation between layers during a print, a lower failure rate, and also faster print times.

He also added resin management with a peristaltic pump. This reduces the size of the build vat, and less resin will be exposed to the elements and wasted. It also means that the printer can run unattended. In the resin handling area of the printer he’s also added a carbon air filter. This lets him run higher performing resins without gassing him out of house and home with fumes.

We like how [Dan] just runs right ahead and puts the printer together. He even points out kludges on the machine that are holding it together long enough for him to print a more functional part for the 3D printer– on the 3D printer. We look forward to the next installment.

Correcting Color Blindness With DLP Projectors

About five percent of the population is colorblind to one degree or another, and for them seeing the entire spectrum from Roy to Biv is simply impossible. Their eyes simply don’t have the cones to detect certain colors. The brain is the weirdest machine on the planet, though, and with the right tricks of light, even the colorblind can see more colors than they’re accustomed to. That’s the idea behind [PointyOintment]’s entry for the 2016 Hackaday Prize: color blindness correcting goggles.

Any device that claims to correct color blindness comes with a few caveats and a slightly loose interpretation of what ‘color blindness correcting’ actually is. For the same reason you can’t see deep infrared, someone with color blindness cannot distinguish between two colors; the eye simply doesn’t have the sensors to see a specific color of light. This doesn’t mean the ability to distinguish color in color blind individuals can’t be improved, though. The EnChroma glasses use an optical notch filter to block all colors between blue and green, and between green and red. This works, because the human brain is weird enough and can adapt to nearly anything.

[PointyOintmen] isn’t going with an optical notch filter. He’s using spinning color discs from a DLP projector and 3D ‘shutter’ glasses to present the world in different shades of color many times a second. It’s weird, untested, and will take a few hours to get used to, but it is a very interesting idea. Will it allow color blind people to see more colors? That’s a semantic issue, but if you define ‘seeing color’ as being able to differentiate between two different colors, yes, it will.

Hacklet 88 – Projector Projects

Everyone loves a big screen TV. Back in the old days, anything over 27 ” was considered big. These days if you’re not sporting at least 50″, you’ll end up with display envy. One thing hasn’t changed though, those who want to go really, really big get into projectors. Hacking and projectors seem to go hand in hand. Anyone else remember those old DIY projection setups where the user would put their TV in a box upside down? This week’s Hacklet is all about projector hacks!

hushWe start with [Chaz] with Projector Hush Box . [Chaz] had a good projector, but still found himself with a problem. Projectors generate a lot of heat, which is dissipated via a fan. For whatever reason, projector companies seem to pick the loudest fans available. [Chaz’s] solution is to put the projector inside a box. Done right, this makes for a quiet projector. Done wrong, it makes an oven. [Chaz] projector hasn’t caught fire yet, so we think he did it right. Two quiet and efficient PC fans direct air through the box, and around baffles which keep the noise down. An anti-reflective coated glass window lets the light out but keeps the noise in. Sound deadening foam helps cut the sound down even further.

led-projNext up is [ric866] with 100w LED projector conversion. The killer with projectors these days are the bulbs. In some cases it’s more cost-effective to buy a new projector than to replace the bulb in an aging one. That’s how [ric866] ended up with a pair of old NEC projectors – one with a working bulb, and one without. Bulbs for this model aren’t cheap at £100. [ric866] found a cheap replacement in a 100 Watt LED. The LED in question only cost £8.99 from everyone’s favorite auction site. LEDs may be efficient, but anyone who’s played with powerful LEDs can tell you they still get hot. [ric866] had to cut up the projector’s case a bit to fit in a heat sink and fan. He also had to spend some time bypassing the various case interlock switches. The final products color calibration looks to be a bit off, but not too shabby for a quick mod!

baffle[Tom_VdE] is serious about recycling. He isn’t one to let an old laptop go to waste when it can be turned into a projector! Remember the “TV in a box” kit we mentioned up in the title? This is the modern version of that same idea. [Tom] tore down the laptop’s LCD and placed it in a CRT monitor case with the appropriate lenses. A setup like this needs length, and focus adjustments. [Tom] managed all that by building a collapsible baffle out of plywood. A build like this needs a lot of light, so [Tom] is using a 100 Watt LED (or two). A water cooling system will keep the LED’s from melting down. [Tom] is still in the prototype phase, but we can’t wait to see his first movie night with this upcycled laptop.

sensorcalFinally, we have [Alex] who built Automatic projector calibration, project #161 on Hackaday.io. [Alex] took his inspiration from [Johnny Chung Lee] to build a system which can map a projector to any angle, size, or position. The secret is phototransistors embedded in the corners of a rectangular piece of foamboard. An Arduino reads the phototransistors while the projector runs a calibration routine. [Alex] switched over to a scanning line from [Johnny’s] original binary pattern. The scan isn’t quite as fast as the binary, but it sure looks cool. Once the positions of the sensors are known, it’s just a matter of mapping the entire screen to a smaller piece of real estate. Toss in a few neat transitions, and you’ve got an awesome demo.

If you want to see more projector projects, check out our new projector project list! If I missed your project, don’t be shy, just drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Astoundingly Great $60 3D Printer called Chimera Bests Your Printer

When most people think of 3D printing, they think of Fused Deposition Modelling (FDM) printers. These work by heating a material, squirting it out a nozzle that moves around, and letting it cool. By moving the nozzle around in the right patterns while extruding material out the end, you get a part. You’ve probably seen one of the many, many, many FDM printers out there.

Stereolithography printing (SLA) is a different technique which uses UV light to harden a liquid resin. The Chimera printer uses this technique, and aims to do it on the cheap by using recycled parts.

First up is the UV light source. DLP projectors kick out a good amount of UV, and accept standard video inputs. The Mitsubishi XD221u can be had for about $50 off eBay. Some modifications are needed to get the focus distance set correctly, but with that complete the X and Y axes are taken care of.

For the Z axis, the build platform needs to move. This was accomplished with a stepper motor salvaged from a disk drive. An Arduino drives the motor to ensure it moves at the right rate.

Creation Workshop was chosen as the software to control the Chimera. It generates the images for the projector, and controls the Z axis. The SLA process allows for high definition printing, and the results are rather impressive for such a cheap device. This is something we were just talking about yesterday; how to lower the cost of 3D printers. Obviously this is cheating a bit because it’s banking on the availability of cheap used parts. But look at it this way: it’s based on older technology produced at scale which should help a lot with the cost of sourcing this stuff new. What do you think?

Digital Light Processing, So Many Tiny Mirrors

Did you know there are a million little mirrors flickering back and forth, reflecting light within some modern projectors; like a flip-dot display but at the micro level? In his video, [Ben Krasnow] explains the tiny magic at work in DLP, or digital light processing technology with a scaled up model he constructed of the moving parts.

LCD projectors work much like old slide projectors. Light is shined through a transparent screen containing the image, which is then focused and enlarged through a lens. DLP projectors however achieve the moving image in a slightly different way. A beam of focused light is shined onto a chip equipped with an array of astonishingly small mirrors. When the mirror is flipped in one direction, it reflects the light out through the lens and creates a visible pixel. When the mirror is tilted the opposite direction, no light is reflected and the pixel is dark. All of these tiny moving parts are actuated by means of static electricity, and since a pixel can effectively only either be in an on or off state without any range of value in-between, the pixel must flutter at a rate fast enough to achieve the illusion of intensity, much like pulsing an LED to create a dimming effect.

In addition to slicing open the protective casing of one of these tiny micro-mirrored chips to give us a look at their physical surface under a microscope, [Ben] also built his own functioning matrix from tiles of mirrors and metal washers sandwiched around pieces of string. A wound electromagnet positioned behind each tile tilts the pixel into position when a current is run through the wire — although he didn’t sink the time needed to build out the full array in this manner (and we don’t blame him). If you do have the time and add in a high powered flash-light, this makes for an awesome way to shine messages on your roommate’s wall.

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