Schlieren On A Stick

August 25, 2020 by Bryan Cockfield 10 Comments

Schlieren imaging is a technique for viewing the density of transparent fluids using a camera and some clever optical setups. Density of a fluid like air might change based on the composition of the air itself with various gasses, or it may vary as a result of a sound or pressure wave. It might sound like you would need a complicated and/or expensive setup in order to view such things, but with a few common things you can have your own Schlieren setup as [elad] demonstrates.

His setup relies on a cell phone, attached to a selfie stick, with a spherical mirror at the other end. The selfie stick makes adjusting the distance from the camera to the mirror easy, as a specific distance from the camera is required as a function of focal length. For cell phone cameras, it’s best to find this distance through experimentation using a small LED as the point source. Once it’s calibrated and working, a circular field of view is displayed on the phone which allows the viewer to see any change in density in front of the mirror.

The only downside of this build that [elad] notes is that the selfie stick isn’t stiff enough to prevent the image from shaking around a little bit, but all things considered this is an excellent project that shows a neat and useful trick in the photography/instrumentation world that could be useful for a lot of other projects. We’ve only seen Schlieren imaging once before and it used a slightly different method of viewing the changing densities.

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Vizy The AI Camera Aims To Ease Machine Vision

August 17, 2020 by Donald Papp 17 Comments

Cameras are getting smarter and more capable than ever, able to run embedded machine vision algorithms and pull off tricks far beyond what something like a serial camera and microcontroller board would be capable of, and the upcoming Vizy aims to be even smarter and easier to use yet. Vizy is the work of Charmed Labs, and this isn’t their first foray into accessible machine vision. Charmed Labs are the same folks behind the Pixy and Pixy 2 cameras. Vizy’s main goal is to make object detection and classification easy, with thoughtful hardware features and a browser-based interface.

Vizy can identify common birds with “Birdfeeder”, one of the several built-in applications that uses local processing only.

The usual way to do machine vision is to get a USB camera and run something like OpenCV on a desktop machine to handle the processing. But Vizy leverages a Raspberry Pi 4 to provide a tightly-integrated unit in a small package with a variety of ready-to-run applications. For example, the “Birdfeeder” application comes ready to take snapshots of and identify common species of bird, while also identifying party-crashers like squirrels.

The demonstration video on their page shows off using the built-in high-current I/O header to control a sprinkler, repelling non-bird intruders with a splash of water while uploading pictures and video clips. The hardware design also looks well thought out; not only is there a safe shutdown and low-power mode for the Raspberry Pi-based hardware, but the lens can be swapped and the camera unit itself even contains an electrically-switched IR filter.

Vizy has a Kickstarter campaign planned, but like many others, Charmed Labs is still adjusting to the changes the COVID-19 pandemic has brought. You can sign up to be notified when Vizy launches; we know we’ll be keen for a closer look once it does. Easier machine vision is always a good thing, because it helps free people to focus on clever ideas like machine vision-based tool alignment.

Building A Gimballed Motorcycle Helmet Camera From Scratch

August 16, 2020 by Mike Szczys 10 Comments

[Nixie Guy] has hit all of important design elements in a single motorcycle helmet-cam project which packs in so much that the build log spans three posts. These cameras need to stand up to the elements and also to being pelted by insects at 80 MPH. They need to attach securely to the helmet without interfering with vision or movement of the head. And you should be able to adjust where they are pointing. The balance of features and cost available in consumer cameras make this list hard to satisfy — but with skills like these the bootstrapped camera came out great!

Where can you get a small, high quality camera? The drone industry has been iterating on this problem for a decade now and that’s where the guts of this creation come from. That produced an interesting issue, the board of the CADDX Turtle V2 camera gets really hot when in use and needs to have air flowing over it. So he threw a custom-milled heat sink into the side of the SLA resin printed housing to keep things somewhat cool.

Since the mill was already warmed up, why not do some mold making? Having already been working on a project to use a casting process for soft PCB membranes, this was the perfect technique to keep the buttons and the SD card slots weather tight on the helmet cam. A little pouch battery inside provides power, and the charging port on the back is a nice little magnet job.

Everything came together incredibly well. [Nixie Guy] does lament the color of the resin case, but that could be easily fixed by reprinting with colored resin.

While you’re bolting stuff onto your helmet, maybe some excessive bling is in order?

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OAK Vision Modules Help You See The Forest And The Trees

August 9, 2020 by Roger Cheng 13 Comments

OpenCV is an open source library of computer vision algorithms, its power and flexibility made many machine vision projects possible. But even with code highly optimized for maximum performance, we always wish for more. Which is why our ears perk up whenever we hear about a hardware accelerated vision module, and the latest buzz is coming out of the OpenCV AI Kit (OAK) Kickstarter campaign.

There are two vision modules launched with this campaign. The OAK-1 with a single color camera for two dimensional vision applications, and the OAK-D which adds stereo cameras for that third dimension. The onboard brain is a Movidius Myriad X processor which, according to team members who have dug through its datasheet, have been massively underutilized in other products. They believe OAK modules will help the chip fulfill its potential for vision applications, delivering high performance while consuming low power in a small form factor. Reading over the spec sheet, we think it’s fair to call these “Ultimate Myriad X Dev Boards” but we must concede “OpenCV AI Kit” sounds better. It does not provide hardware acceleration for the entire OpenCV library (likely an impossible task) but it does cover the highly demanding subset suitable for Myriad X acceleration.

Since the campaign launched a few weeks ago, some additional information have been released to help assure backers that this project has real substance. It turns out OAK is an evolution of a project we’ve covered almost exactly one year ago that became a real product DepthAI, so at least this is not their first rodeo. It is also encouraging that their invitation to the open hardware community has already borne fruit. Check out this thread discussing OAK for robot vision, where a question was met with an honest “we don’t have expertise there” from the OAK team, but then ArduCam pitched in with their camera module experience to help.

We wish them success for their planned December 2020 delivery. They have already far surpassed their funding goals, they’ve shipped hardware before, and we see a good start to a development community. We look forward to the OAK-1 and OAK-D joining the ranks of other hacking friendly vision modules like OpenMV, JeVois, StereoPi, and AIY Vision.

Bringing The Pi Camera Into Focus With LEGO

July 22, 2020 by Moritz v. Sivers 6 Comments

Ever since the high-quality camera for the Raspberry Pi was released a few months back it has been the center of attention for many hacks. In this quick build [Martin Mander] shows us how to make a servo-powered focusing mechanism entirely from LEGO.

The inspiration for this project came to him while he was working on his 1979 Merlin Pi Camera and found that setting the focus just right is vital in order to get good quality pictures. So he set himself the goal to build a mechanism that allows him to focus the camera precisely and remotely.

It is the plethora of LEGO-compatible parts that are available off-the-shelf that make such a project possible without the use of any 3D printed components. He not only found a LEGO-compatible continuous rotating servo but also a LEGO-compatible case for the Pi, and a LEGO cogwheel which almost fits exactly onto the camera lens. He also added a tripod mount to the case that allows him to set up the camera anywhere. The camera and focussing mechanism are controlled with a custom GUI based on guizero Python 3 library and the camera can be accessed remotely via VNCViewer.

If you prefer 3D printing over LEGO there are also other stylish Raspi HQ camera builds.

Video after the break.

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A Stylish Raspberry Pi Camera

July 21, 2020 by Jenny List 4 Comments

The Raspberry Pi HQ camera module is an exciting product that for the first time puts something close to a decent quality interchangeable lens camera into the hands of hardware hackers. It’s already attracted the attention of those who have a wish to explore the boundaries of camera form factors. Our latest entrant in this field comes courtesy of [BBまどーし], who has opted for a very good 3D-printed analog of a conventional compact camera.

On the front as you might expect is the module, concealed behind a smart plastic ring. Behind that is a battery compartment, concealing not the brace of 18650s or the bare LiPo pouch that you might expect, but a 10,400 mAH USB power bank. Behind that is something approaching a conventional Raspberry Pi case, designed to take a Hyperpixel screen. The battery might seem an unadventurous choice, but it serves to highlight just how much bang for your buck can now be found in compact power banks. It may not have a hacker aesthetic, but you can’t argue with its cost and simplicity.

The details are the interesting part of this design, for instance it has a standard accessory shoe printed into its top. There is also a shutter button, but they admit to not being a software wizard enough to get it working. Perhaps a quick look at this Pi Camera in a 1970s Merlin game would be in order.

An HDMI Monitor From Your Phone

July 18, 2020 by Jenny List 46 Comments

Digital video has proceeded to the point at which we have near-broadcast-quality HD production capabilities in the palm of our hand, and often for a surprisingly affordable price. One area in which the benefits haven’t quite made it to our wallets though is in the field of small HD monitors of the type you might place on top of a camera for filming. It’s a problem noted by [Neon Airship], who has come up with a solution allowing the use of an Android mobile phone as an HDMI monitor. Since many of us will now have a perfectly capable older phone gathering dust, it’s an attractive proposition with the potential to cost very little.

The secret isn’t the most elite of hacks in that it uses all off-the-shelf hardware, but sometimes that isn’t the only reason to be interested in a project such as this one. [Neon] is using an HDMI-to-USB capture card of the type that has recently become available from the usual sources for an astoundingly small sum. When paired with a suitable USB OTG cable, the adapter can be seen by the phone as just another webcam.

We see him try a few webcam viewer apps including one that rather worryingly demands a direct APK download, and the result is a very good quality HDMI monitor atop his camera that really didn’t break the bank. Sometimes the simplest of solutions deliver the most useful of results.

This is something of special interest to those of us who experiment with our own camera form factors.

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