Make Yourself A Megamind With A Hypercentric Camera

June 4, 2023 by Dan Maloney 4 Comments

Sometimes, all it takes to learn something new is a fresh perspective on things. But what’s to be learned from reversing your perspective completely with a hypercentric lens? For one thing, that you can make humans look really, really weird.

To be fair, there’s a lot to the optical story here, which [volzo] goes over in ample detail. The short version of it is that with the right arrangement of optical elements, it’s possible to manipulate the perspective of a photograph for artistic effect, up to the point of reversing the usual diminishment of the apparent size of objects in the scene that are farther away from the camera. Most lenses do their best to keep the perspective of the scene out of this uncanny valley, although the telecentric lenses used in some machine vision systems manipulate the perspective to make identical objects within the scene appear to be the same size regardless of their distance from the camera. A hypercentric lens, on the other hand, turns perspective on its head, making near objects appear smaller than far objects, and comically distorts things like the human face.

[volzo]’s hypercentric camera uses a 700-mm focal length Fresnel lens mounted on a motorized gantry, which precisely positions a camera relative to the lens to get the right effect. A Raspberry Pi controls the gantry, but it’s not strictly needed for the hypercentric effect to work. Lighting is important, though, with a ring of LEDs around the main lens providing even illumination of the scene. The whole setup as well as the weirdly distorted portraits that result are shown in the video below.

If these bizarrely distorted faces look familiar, you might be recalling [Curious Marc]’s head-enlarging wearable.

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AI Camera Imagines A Photo Of What You Point It At

June 2, 2023 by Lewin Day 21 Comments

These days, every phone has a camera, and few of us are ever without one. [Bjørn Karmann] has built an altogether not-camera, though, in the form of the Paragraphica, powered by artificial intelligence.

The Paragraphica doesn’t actually take photographs at all. Instead, it uses GPS to determine the user’s current position. It then feeds the address, time of day, weather, and temperature into a paragraph which serves as a prompt for an AI image generator. It also uses data gathered from various APIs to determine points of interest in the immediate area, and feeds those into the prompt as well. It then generates an artificial image that is intended to bear some resemblance to the prompt, and ideally, the real-world scene. In place of a lens, it bears a 3D printed structure inspired by the star-nosed mole, which feels its way around in lieu of using its eyes.

Three dials on the Paragraphica control its action. The first dial controls the radius of the area which the prompt will gather data about; it’s akin to setting the focal length of the lens. The second dial provides a noise seed value for the AI image generator, and the third dial controls how closely the AI sticks to the generated textual prompt.

The results are impressive, if completely false and generated from scratch. The Paragraphica generates semi-believable photos of a crowded alley, a public park, and a laneway full of parked cars. It’s akin to telling a friend where you are and what you’re seeing over the phone, and having them paint a picture based on that description.

Through their unique abilities and stolen data sets, AI image generators are proving controversial to say the least. As all good art does, Paragraphica explores this and raises new questions of its own.

IR Camera Is Excellent Hacking Platform

June 1, 2023 by Bryan Cockfield 14 Comments

While there have been hiccups here and there, the general trend of electronics is to decrease in cost or increase in performance. This can be seen in fairly obvious ways like more powerful and affordable computers but it also often means that more powerful software can be used in other devices without needing expensive hardware to support it. [Manawyrm] and [Toble_Miner] found this was true of a particular inexpensive thermal camera that ships with Linux installed on it, and found that this platform was nearly perfect for tinkering with and adding plenty of other features to turn it into a much more capable tool.

The duo have been working on a SC240N variant of the InfiRay C200 infrared camera, which ships with a Hisilicon SoC. The display is capable of displaying 25 frames per second, making this platform an excellent candidate for modifying. A few ports were added to the device, including USB and MicroSD, and which also allows the internal serial port to be accessed easily. From there the device can be equipped with the uboot bootloader in order to run essentially anything that could be found on any other Linux machine such as supporting a webcam interface (and including a port of DOOM, of course). The duo doesn’t stop at software modifications though. They also equipped the camera with a lens, attached magnetically, which changes the camera’s focal length to give it improved imaging capabilities at closer ranges.

While the internal machinations of this device are interesting, it actually turns out to be a fairly capable infrared camera on its own as well. The hardware and software requirements for these devices certainly don’t need a full Linux environment to work, and while we have seen thermal cameras that easily fit in a pocket that are based on nothing any more powerful than an ESP32, it does tend to simplify the development process dramatically to include Linux and a little more processing power if you can.

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A Bullet Time Video Booth You Can Build

May 27, 2023 by Dave Rowntree 8 Comments

[Sebastian Staacks] built a video booth for his wedding, and the setup was so popular with family, that it was only fitting to do one better and make some improvements to the setup, Matrix-style. The “bullet time” video effect was introduced by the classic movie franchise and makes for a splendid video transition effect for video montages.

Hardware-wise, the effect is pretty expensive, requiring many cameras at various angles to be simultaneously triggered, in order to capture the subject in a fixed pose with a rotating camera. Essentially you need as many cameras as frames in the sequence, so even at 24 frames per second (FPS), that’s a lot of hardware. [Sebastian] cheated a bit, and used a single front-facing camera for the bulk of the video recording, and twelve individual DSLRs covering approximately 90 degrees of rotation for the transition. More than that is likely impractical (not to mention rather expensive) for an automated setup used in as chaotic an environment as a wedding reception! So, the video effect is quite the same as in the movies, as this is a fixed pose, but it still looks pretty good.

A Pico-W hidden in there providing a BT connected interface button

[Sebastian] did consider going down the Raspberry Pi plus Pi-cam route, but once you add in a lens and the hassle of the casing and mounting hardware, not to mention availability and cost, snagging a pile of old DLSRs looks quite attractive. Connectivity to the camera is a simple 3.5 mm jack for the focus and trigger inputs, with frames read out via a USB connection.

For practical deployment, the camera batteries were replaced with battery eliminator adapters which step-up the 5 V from the USB connection to the 7.4 V the cameras need, but the current spike produced by the coordinated trigger of all twelve cameras overwhelmed any power supply available. The solution, to be practical, and not at all elegant, is to just have lots of power supplies hidden in a box. Sometimes you’ve just got a job to do.

Reproducing this at home might be a bit awkward unless you have exactly the same hardware to hand, but the principles are sound, and there are a few interesting details to dig into, if you were so inclined.

We’ve seen a few takes on the bullet-time effect over the years. We featured a Raspberry Pi-based hack, a couple of years back, and earlier still, someone even built a rig to take bullet-time videos of Tesla coil discharges, because why not?

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A Vintage Polaroid Camera Goes Manual

May 18, 2023 by Jenny List 5 Comments

There once was a time when all but the most basic of fixed focus and aperture cameras gave the photographer full control over both shutter speed and f-stop. This allowed plenty of opportunity to tinker but was confusing and fiddly for non-experts, so by the 1960s and ’70s many cameras gained automatic control of those functions using the then quite newly-developed solid state electronics. Here in 2023 though, the experts are back and want control. [Jim Skelton] has a vintage Polaroid pack film camera he’s using with photographic paper as the film, and wanted a manual exposure control.

Where a modern camera would have a sensor in the main lens light path and a microcontroller to optimize the shot, back then they had to make do with a CdS cell sensing ambient light, and a simple analog circuit. He considered adding a microcontroller to do the job, but realized that it would be much simpler to replace the CdS cell with a potentiometer or a resistor array. A 12-position switch with some carefully chosen resistor values was added, and placed in the camera’s original battery compartment. The final mod brought out the resistors and switch to a plug-in dongle allowing easy switching between auto and switched modes. Result – a variable shutter speed Polaroid pack camera!

Sadly the film for the older Polaroid cameras remains out of production, though the Impossible Project in the Netherlands — now the heirs to the Polaroid name — brought back some later versions and have been manufacturing them since 2010. Hackers haven’t been deterred though and have produced conversions using Fuji Instax film and camera components, as with this Polaroid portrait camera, and [Jim]’s own two-camera-hybrid conversion.

A Non-Destructive Digital Back For A Classic Leica

May 12, 2023 by Jenny List 16 Comments

As digital photography has become so good, perhaps just too good, at capturing near-perfect pictures, some photographers have ventured back into the world of film. There they have found the imperfections requiring technical skill to cope with that they desire, but they’ve also come face-to-face with the very high cost and sometimes sketchy availability of film stocks. From this has come the so-called post-digital movement which marries analog cameras and lenses with digital sensors, and of this a particularly nice example comes from [Michael Suguitan]. He’s taken a classic Leica M2 rangefinder camera, and built a new back for it containing a Raspberry Pi Zero and sensor.

Perhaps the best thing about this conversion, and something which should propagate forward into other builds, is the way it does not hack or modify the original camera beyond the replacement of the already-removable back. A vintage Leica is a pricey item, so it would be a foolhardy hacker who would proceed to gut it for a digital conversion. Instead he’s mounted everything that makes a digital camera, the sensor, Pi Zero, and screen board, behind the camera body. The Pi shutter trigger comes from the Leica’s flash terminal, meaning that there’s plenty of time for it to take a photo while the shutter is open.

He’s admirably preserved the usage and properties of the Leica, and his photographs as can be seen in the video below the break bear testament to what is possible with the camera. He still has to work with the tiny sensor size though, meaning that all photographs are at a much higher zoom level than on the original. We would love to see a camera conversion like this one that incorporates appropriate lenses to bring the picture to focus on this small sensor.

We won’t own a Leica any time soon, but we like this conversion. It’s by far the most sympathetic, but it’s not the first rangefinder conversion we’ve seen.

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Machine Vision Automates Trainspotting With Unique Full-Length Portraits

May 2, 2023 by Dan Maloney 11 Comments

As hobbies go, trainspotting is just as valid a choice as any — we don’t judge. But it does present certain logistical challenges, such as having to be in visual range of a train to be able to spot it. There’s also the fact that trains are very large objects, and they tend to move very fast. What’s a railfan to do?

If you’re also technically minded, you might try building an automatic trainspotting bot like [jo-m] has. It looks like the hardware end of “Trainbot” is pretty simple since it has been tested on both x86 and Raspberry Pi, and supports both video4linux and Pi cam. The magic is in the software, which is able to detect a train entering the frame, record images, and then stitch them together into one long image. The whole thing is coded in Go and has some interesting bits, like a custom image patch mapping package.

Trainbot gives an unusual view of a train, one that most of us accustomed to watching a train pass at a crossing have never seen. By stitching small chunks of the train as it passes, Trainbot is able to show the entire train in a single image, which would be impossible to do except for being very, very far away from the track. [jo-m] also built a web interface for Trainbot where you can check out the comings and goings yourself. Each passing train’s image is accompanied by data like its velocity and acceleration, length of the train, and time of passage. There’s also a GIF of the original source video, which is pretty cool.

Here in the States, we don’t have a lot of passenger trains to spot, but we do have some really long freight trains. It’d be interesting to see how this works with a train that’s over a mile long; that would be quite an image. Looks like someone at least has the hardware in place to give it a try.