Camera Trick Lets You See Sound Waves In Falling Water

March 14, 2013 by Mike Szczys 27 Comments

From this still image you’d think the hose dispensing the water is being moved back and forth. But watch the video after the break and you’ll see the hose is quite steady, as is the standing wave of water. It’s bizarre to be sure. Knowing how it works makes cognitive sense, but doesn’t really diminish the novelty of the demonstration.

This is the second time [Brasspup] has posted a video of this phenomenon. The newest version does a great job of showing several different patterns. But even the first segment from a year ago, which has over 4 million hits, shows the water moving against gravity. We also saw a similar rig in a links post a year ago.

We’d call it an optical illusion but it’s really more of a technological illusion. The water is falling past a sub-woofer speaker which is tuned to 24 Hz. At the same time, the camera filming the demonstration is capturing 24 frames per second. As was mentioned then, it’s much like flashing a light to freeze the water in mid-air. But the flashing of the frames is what causes this effect.

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ShuttAVR Can Snap A Pic Or Serve As An Intervalometer

March 14, 2013 by Mike Szczys 8 Comments

shuttAVR-intervalometer-hack

This project started as a simple microcontroller replacement on this IR camera remote control PCB. But the soldering job went rather badly for [Balthamos] so he changed things up and designed his own simple AVR remote shutter release and intervalometer.

The DIP chip seen with most of its legs bent backwards is the ATtiny25 which makes the system work. It’s patched into the traces for the battery connections, button (on the other side of the board) and the IR LED he’s pinching with his left hand. Point it at a Cannon camera and push the button to snap a photo. But as you can see in the clip after the break it also serves as an intervalometer; letting him take several pictures with a user-defined pause between each. That mode is selected by first pressing and holding the button. Once released the chip waits for a second button press to register the delay. The new circuit still fits in the original case after just a bit of alteration to it.

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Time-lapse Dolly Uses Some Stock Parts And A Bit Of Machining Work

March 6, 2013 by Mike Szczys 7 Comments

linear-carriage-for-time-lapse-photography

[Ben] just finished building this time-lapse dolly and decided to share his experience. We think he struck just the right balance of diy and commercially available materials to create a rig that is stable yet relatively inexpensive.

The project was inspired by Project Chronos. It gives a lot of details about the drive electronics and code used, but there are some gaps in the instructions for building the track itself. [Ben] forged ahead, purchasing linear bearings and a double-guide rail from IGUS. He didn’t mention the price on that item but we found 1000mm of the stuff (about 40 inches) for under $75 so it’s not outrageous. The part he couldn’t get for a reasonable price was precision thread bar. He ended going with regular threaded rod and a couple of nuts combined with a spring mechanism to keep the sled steady. That seems to work just fine. You can see the rod bouncing a bit in the clip after the break but it doesn’t harm the stability of the captured images.

The end stops including the one to which the stepper motor is mounted are his own work. It sounds like they required a bit more fabrication work than he was planning on but we figure if you don’t challenge your skill set you never get any better.

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Building A Remote Control For A Cable Release Camera

March 3, 2013 by Mike Szczys 10 Comments

wireless-shutter-for-mechanical-camera

A lot of the remote shutter and intervalometer hacks we see are simplified by the camera’s built-in Infrared or other shutter techniques. But this camera doesn’t have a simple way to electronically trigger the shutter. The Fuji x100 is a digital camera, but it uses a cable release mechanism. The box you see on top is [Andy’s] method of making a remote shutter release for it.

The solution for “remote” triggering is that black cable which physically attaches to the shutter button. Just depress the plunger at the opposite end and a picture will be snapped. This process is automated with the use of a hobby servo hidden inside the box. It’s driven by an Arduino which is also monitoring the receiver. You could use just about any remote thanks to the Arduino’s flexibility in interfacing with hardware (we would have gone with a Bluetooth module and our smartphone). [Andy] chose to use an RF remote and receiver for a different camera.

Revolving Camera Mount Helps To Capture 3D Video-game Assests

March 1, 2013 by Mike Szczys 24 Comments

3d-image-capture

Here’s a camera rig that makes it a snap to produce photorealistic 3D models of an object. It was put together rather inexpensively by an indie game company called Skull Theatre. They published a couple of posts which show off how the rig was built and how it’s used to capture the models.

They’re using 123D, a software suite which is quite popular for digitizing items. The rig has a center table where an object is placed, and a movable jig which holds three different cameras (or one camera for three rotations). You can see the masking tape on the floor which marks the location for each shot. These positions are mapped out in the software so that it has an easy time putting them all together. The shaft which connects the jig to the base is adjustable to accommodate large or small items.

One thing that we found interesting is the team’s technique for dealing with reflections. They use a matte spray to make those surfaces less reflective. This helps 123D do its job but also allows them to map reflective surface more accurately using the game engine.

Build An Eye Tracking Headset For $90

February 12, 2013 by Brian Benchoff 41 Comments

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Eye tracking is a really cool technology used in dozens of fields ranging from linguistics, human-computer interaction, and marketing. With a proper eye tracking setup, it’s possible for a web developer to see if their changes to the layout are effective, to measure how fast someone reads a page of text, and even diagnose medical disorders. Eye tracking setups haven’t been cheap, though, at least until now. Pupil is a serious, research-quality eye tracking headset designed by [Moritz] and [William] for their thesis at MIT.

The basic idea behind Pupil is to put one digital camera facing the user’s eye while another camera looks out on the world. After calibrating the included software, the headset looks at the user’s pupil to determine where they’re actually looking.

The hardware isn’t specialized at all – just a pair of $20 USB webcams, a LED, an infrared filter made from exposed 35mm film negatives, and a 3D printed headset conveniently for sale at Shapeways.

The software for Pupil is based on OpenCV and OpenGL and is available for Mac and Linux. Calibration is easy, as seen in the videos after the break, and the results are amazing for an eye tracking headset thrown together for under $100.

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Quantifying Cloudiness With OpenCV

February 7, 2013 by Eric Evenchick 12 Comments

The Shard is the tallest building in Western Europe, and has a great view of London. The condos in the building are very expensive, and a tourist ride to the top of the building costs £24.95.

Since the value of the view is so high, [Willem] wanted to quantify the quality of the view at any given time. His solution is the Shard Rain Cam. This device combines a Logitech webcam with a Raspberry Pi to capture a time-lapse set of images. These images are fed to a Python script using OpenCV which quantifies the cloudiness.

[Willem] also had to build a weatherproof enclosure with a transparent window for the camera and RPi. ‘Clingfilm’, which is British for saran wrap, and mineral oil is used to improve the waterproofing of an IP54 rated enclosure.

The resulting data is displayed on www.whatcaniseefromtheshard.com, which provides an indication of whether or not the view is worth £24.95. All of the Python code is available, and is a good starting point for learning about image processing with OpenCV.