[jwcrawley] is busy planning for the Makevention coming up in Bloomington, Indiana in late August. One problem when working any con is manning the door; it’s a good idea to know how many people are there, and you can’t double count people. Previously, the volunteers used dead trees to estimate how many people have turned up. This year they might go with a more technological solution: face recognition and tracking.
The project is called uWho, and it uses the faceRecognizer class in OpenCV. The purpose of the entire project is to identify who someone is from previous frames. If your face is unknown to the program, your likeness – rather, a few points of data – are added to the database of faces. It’s simple, and according to [jwcrawley], it works.
While this is technically the best way to count how many unique people show up to Makevention, there will be some discussions to see if this solution is appropriate. The program only saves unique data from a face locally, and does nothing online. It’s less evil than whatever Facebook does, but there are obvious privacy implications here.
Link to the Makevention.
Logic Noise is all about using logic circuits to make sounds. Preferably sound that will be enjoyable to hear and useful for making music. This week, we’ll be scratching the surface of one of my favorite chips to use and abuse for, well, nearly anything: the 4051 8-way analog switch. As the name suggests, you can hook up eight inputs and select one from among them to be connected up to the output. (Alternatively, you can send a single input to one of eight destinations, but we won’t be doing that here.)
Why is this cool? Well, imagine that you wanted to make our oscillator play eight notes. If you worked through our first installment, you built an abrasive-sounding but versatile oscillator. I had you tapping manually on eight different resistors or turning a potentiometer to eight different positions. This week, we’ll be letting the 4051 take over some of the controls, leaving us to do the more advanced knob twiddling.
Continue reading “Logic Noise: The Switching Sequencer Has the Beat”
[edyb] uses his relatively inexpensive Cannon camera quite a bit. However, in dark areas or extreme closeups, the camera’s image quality leaves something to be desired. [edyb] hopped on the ‘net and found out that a ring light may cure his photo faux pas. Ring lights are nothing new but nothing existed for his lower-end point and shoot camera. With a USB-powered lamp and a spare AA battery pack kicking around, [edyb] decided to make his own.
First, the USB lamp was disassembled, luckily the LEDs were already laid out in a ring shape. The clear protective housing and gooseneck were discarded and the remaining PCB ring was glued directly to the camera. A female USB jack was then glued to the top of the camera and soldered to the two leads connected to the lamp’s PCB. The AA battery holder received a small switch and a male USB plug, also courtesy of a few dabs of glue. The now-assembled battery pack plugs directly into the camera via the USB connector and is its only method of attachment.
The utilitarian modification may look crude but the results are anything but. Check out this close-up macro shot of a Canadian penny. Not too bad.
[edyb] has done some similar mods to other cameras, attaching components with magnets and even using an old Blackberry battery to power the LEDs showing that there is no one way to solve a problem. Check out the video after the break…
Continue reading “Inexpensive Ring Light Makes Macro Photos Easy”
Time-lapse photography is always a fun way to show off the build process of a project – but sometimes it can get a bit boring and repetitive. To add a new dynamic, why not try a moving time-lapse? It’s not actually that hard to build a time-lapse slider rig. And you can do it with, or without a microcontroller.
[Charlie] built this slider rig out of square aluminum tube stock which is cheap and easy to work with. It’s also a great candidate for using pop-rivets which can speed up the assembly considerably. The camera bogey uses aluminum angle stock with skateboard bearings to ride along the track. Altogether the rig is four feet long and about 6″ wide.
To pull the camera back and forth, [Charlie] has a 0.5RPM geared motor from Servo-City which results in a travel time of about 5400 seconds (90 minutes). While there aren’t any demo videos of the rig in action, we imagine it’d produce some pretty clean motion. And thanks to its rigid construction, the camera can be pulled upside down, on angles, and even vertically.
What’s cooler than learning about timers and interrupts on AVRs? Well, if you’re like [Matt], you can use that learning experience to build something useful – in this case, a timer for various camera flashes.
There are two ways to measure the speed of a flash. The first is the lag between when a button is pressed and when the flash goes off. As long as this is consistent, everything’s okay. The second type of speed is the pulse width. When looking at a xenon flash as time vs. brightness, they have a large spike at the beginning followed by a significant amount of decay. LED flashes are pretty much one cycle of a square wave.
To measure both types of flash speed, [Matt] used a $0.50 photodiode an a 3.5mm jack that ties into the flash remote. These bits are wired up to an Arduino, a little bit of fun work with timers and interrupts happens, and [Matt] learns how fast his flash is.
Transcend markets their DrivePro 200 camera for use as a car dashcam. We’re a bit surprised at the quality and apparent feature set for something relegated to a rather mundane task as this. But [Gadget Addict] poked around and found a nice little nugget: you can live stream the video via WiFi; the framerate, quality, and low-lag are pretty impressive. In addition to that, the next hack is just waiting for you to unlock it.
As it stands right now you turn on the camera’s built-in WiFi AP, telnet into two different ports on the device (sending it into smartphone connected mode) and you’ll be able to live stream the view to your computer using RTSP. Great, that in itself is a good hack and we’re sure that before long someone will figure out an automatic way to trigger this. [GA] also found out how to get the thing into script mode at power-on. He hasn’t actually executed any code… that’s where you come in. If you have one of these pull it out and get hacking! It’s a matter put putting files on the SD storage and rebooting. Crafting this file to enable shell access would open up an entire world of hacks, from things like time-lapse and motion sensing to special processing and filtering in real time. We think there’s huge potential so keep us up-to-date as you find new ways to pwn this hardware.
Continue reading “Transcend DrivePro 200 Hack to Stream and Script; Begs for More”
For apparently inexplicable reasons, the price of thermal imaging cameras has been dropping precipitously over the last few years, but there are still cool things you can do with infrared temperature sensors.
A few years ago – and while he was still writing for us – [Jeremy] came across an absurdly clever thermal imaging camera. Instead of expensive silicon, this thermal camera uses a flashlight with an RGB LED, a cheap IR temperature sensor, and a camera set up to take long exposures. By shining this flashlight/IR sensor around a dark room, a camera with a wide-open shutter can record color-coded thermal images of just about anything.
Since then, an interesting product appeared on the market. It’s the Black & Decker TLD100 Thermal Leak Detector, and it’s basically an infrared thermometer and LED flashlight stuffed into one neat package. In other words, it’s the exact same thing we saw two years ago. We’d like to thank at least one Black & Decker engineer for their readership.
[Jeremy] took this cheap, off-the-shelf leak detector and did what anyone would do after realizing where the idea behind it came from. He set up his camera, turned off the lights, and opened the shutter of his camera. The results, like the original post, don’t offer the same thermal resolution as a real thermal camera. That doesn’t mean it’s still not a great idea, though.