Absolute 3D Tracking With EM Fields

[Chris Gunawardena] is still holding his breath on Valve and Facebook surprising everyone by open sourcing their top secret VR prototypes. They have some really clever ways to track the exact location and orientation of the big black box they want people to strap to their faces. Until then, though, he decided to take his own stab at the 3D tracking problems they had to solve. 

While they used light to perform the localization, he wanted to experiment with using electromagnetic fields to perform the same function. Every phone these days has a magnetometer built in. It’s used to figure out which way is up, but it can also measure the local strength of magnetic fields.

Unfortunately to get really good range on a magnetic field there’s a pesky problem involving inverse square laws. Some 9V batteries in series solved the high current DC voltage source problem and left him with magnetic field powerful enough to be detected almost ten centimeters away by his iPhone’s magnetometer.

As small as this range seems, it ended up being enough for his purposes. Using the existing math and a small iOS app he was able to perform rudimentary localization using EM fields. Pretty cool. He’s not done yet and hopes that a more sensitive magnetometer and a higher voltage power supply with let him achieve greater distances and accuracy in a future iteration.

KiCad Traducido al Español

KiCad ya es una gran herramienta para la captura esquemática y el diseño de PCB, pero el software sólo funciona si es posible utilizarlo. Para los mil millones de personas que no hablan inglés, esto significa que el idioma es la barrera más grande al momento de utilizar el mejor software para desarrollo de hardware. En los últimos meses, [ElektroQuark] ha estado liderando esfuerzos de localización al español de KiCad y estos se encuentran finalmente completados. También ha iniciado un foro de KiCad en idioma español para llevar el desarrollo de software hacia uno de los idiomas más hablado del planeta.

SpanishMientras que ha habido otros intentos por localizar KiCad a otros idiomas, la mayoría de estos proyectos se encuentran incompletos. En una actualización de KiCad hace algunos meses, la localización al español ya contaba con algunas cadenas ya traducidas, pero no demasiadas. Los esfuerzos de [ElektroQuark] han acercado KiCad a millones de hablantes nativos de español, no solo algunos de sus menús.

El español es la segunda lengua más hablada del planeta, mientras que el inglés es la tercera. Teniendo en cuenta solamente este hecho, parece absurdo que casi todas las herramientas de software para capturas esquemáticas y diseño de PCB sean localizados sólo al chino o al inglés. Los esfuerzos de [ElektroQuark] por localizar KiCad al español son un gran avance para un ya impresionante software.

SprayPrinter Paints Your Wall, One Pixel At A Time

SprayPrinter is a neat idea. You download a cellphone app, point the camera at a wall, and sweep the wall with a spray can fitted with a (Bluetooth? WiFi?) remote-controlled valve. The phone knows where the nozzle is, and sprays a dot whenever it needs to “paint” the picture of your choosing on the wall.

sprayprinter-estonia-designboom-002-818x500While we’re not sure that we have the patience to paint our walls this way, it’s a cool effect. But even more, we love the idea of using the cellphone camera for location sensing. Many robotics applications do just this with an overhead camera.

Of course, we’d love more detail about how it’s done, but it’s not hard to guess that it’s either a bit of machine vision in the phone, or simpler still, that the spray-can housing has IR LEDs inside that the phone can lock onto. Indeed, the prototype version of the product shown here does look like it has an LED on the opposite side from the orange nozzle.

It wouldn’t be hard to take this to the next level, by adding enough IR LEDs that the camera in your phone can sense orientation as well as location. Heck, by measuring the distances between LEDs, you could probably even get a rough measure of depth. This could open up the use of different nozzles.

Thanks [Itay] for the tip! Some images courtesy SprayPrinter, via designboom.


GPS without GPS

Open Electronics just released a neat little board that can place you on a map without using GPS.

The board works on the basic principles of a cellphone network – the ‘cell’ network is a series of towers that are placed more or less equidistant to each other. Save for the most desolate parts of the country, a cell tower usually communicates with a phone one or two miles away. Usually, several cell towers can be seen, so the position of a cellphone can be pinpointed to within 200-350 feet. Translating cell towers to latitude and longitude is easily done by querying a Google database that was created for the mobile version of Google Maps.

The board itself is a PIC18 microcontroller and a SIM900 GSM module. The firmware available at Open Electronics is pretty impressive – all communication to the board is handled through SMS and the phone can report it’s location to 8 other phones.

It’s pretty impressive to think the same technology that caught [Kevin Mitnick] is now available to the masses. We’re wondering what Hack a Day readers would use this for, so if you have an idea leave a comment.