IPhone Polarizing Camera Solves Filter Orientation Problem Using Flash

July 4, 2016 by Jenny List 6 Comments

One of last year’s Hackaday Prize finalists was the DOLPi, [Dave Prutchi]’s polarimetric camera which used an LCD sheet from a welder’s mask placed in front of a Raspberry Pi camera. Multiple images were taken by the DOLPi at different polarizations and used to compute images designed to show the polarization of the light in each pixel and convey it to the viewer through color.

The polarizer and phototransistor taped to the iPhone.

[Dave] wrote to tip us off about [Paul Wallace]’s take on the same idea, a DOLPi-inspired polarimetric camera using an iPhone with an ingenious solution to the problem of calibrating the device to the correct polarization angle for each image that does not require any electrical connection between phone and camera hardware. [Paul]’s camera is calibrated using the iPhone’s flash. The light coming from the flash through the LCD is measured by a phototransistor and Arduino Mini which sets the LCD to the correct polarization. The whole setup is taped to the back of the iPhone, though we suspect a 3D-printed holder could be made without too many problems. He provides full details as well as code for the iPhone app that controls the camera and computes the images on his blog post.

We covered the DOLPi in detail last year as part of our 2015 Hackaday Prize finalist coverage. You can also find its page on Hackaday.io, and [Dave]’s own write-up on his blog.

Horrible Macro Rig Makes Good Photos

July 1, 2016 by Elliot Williams 19 Comments

We love horrible hacks like this. It’s a lens and a ring of LEDs, taped to a cell phone. Powered through crocodile clips, also taped to the cell phone. There’s nothing professional here — we can think of a million ways to tweak this recipe. But the proof of the pudding is in the tasting.

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Automating A Microscope For CNC Micrographs

June 29, 2016 by Brian Benchoff 2 Comments

[Maurice] is a photographer specializing in micrographs. These very large images of very small things are beautiful, but late last year he’s been limited by his equipment. He needed a new microscope, one designed for photography, that had a scanning stage, and ideally one that was cheap. He ended up choosing a microscope from the 80s. Did it meet all his qualifications? No, but it was good enough, and like all good tools, capable of being modified to make a better tool.

This was a Nikon microscope, and [Maurice] shoots a Canon. This, of course, meant the camera mount was incompatible with a Canon 5D MK III, but with a little bit of milling and drilling, this problem could be overcome.

That left [Maurice] with a rather large project on his hands. He had a microscope that met all his qualifications save for one: he wanted a scanning stage, or a bunch of motors and a camera controller that could scan over a specimen and shoot gigapixel images. This was easily accomplished with a few 3D printed parts, stepper motors, and a Makeblock Orion, an Arduino-based board designed for robotics that also has two stepper motor drivers.

With a microscope that could automatically scan over a specimen and snap a picture, the only thing left to build was a piece of software that automated the entire process. This software was built with Processing. While this sketch is very minimal, it does allow [Maurice] to set the step size and how many pictures to take in the X and Y axis. The result is easy automated micrographs. You can see a video of the process below.

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One Hacker’s Small Tabletop Photo Studio

May 22, 2016 by Gerrit Coetzee 14 Comments

We love good pictures. You know, being worth a thousand words and all. So, after our article on taking good reference photos, we were pleased to see a reader, [Steve], sharing his photography set-up.

Taking good technical photos is a whole separate art from other fields of photography like portraiture. For example, [Steve] mentions that he uses “bullseye” composition, or, putting the thing right in the middle. The standard philosophy on this method is that it’s bad and you are bad. For technical photos, it’s perfect.

[Steve] also has some unique toys in his arsenal. Like a toy macro lens from a subscription chemistry kit. He also showed off his foldscope. Sadly, they appear to no longer be for sale, but we sometimes get by with a loupe held in front of the lens. He also uses things standard in our shop. Such as a gridded cutting mat as a backdrop and a cheap three dollar tripod with spring actuated jaws to hold his phone steady.

In the end, [Steve] mostly shows that a little thought goes a long way to producing a photo that doesn’t just show, but communicates an idea in a better way than just words can manage.

Raspberry Pi Zero Now With Camera Support, Still Only $5

May 16, 2016 by Donald Papp 119 Comments

The latest version (1.3) of everyone’s favorite $5 computer now sports a frequently requested feature: a camera connector. The Pi Zero will now use the same economical camera modules available for the full-sized Raspberry Pi units.

The price of the Pi Zero is unchanged at $5, but there is a small catch. While the Raspberry Pi camera modules themselves will work just fine on the Pi Zero, the usual camera cable they come with will not. The Pi Zero’s camera cable connector is a little smaller than the ones on the full-grown Pi, so it needs a special cable to interface the camera modules to the slightly smaller connector found on the Pi Zero.

This should be good news. The new connector has appeared because another production run is ramping up. Logic points to greater availability of the $5 wonder board, but we’re still not holding our breath.

Adafruit Pi Zero camera cable — Pi Zero with camera module connector cable. [Image source: Adafruit]

With the Pi Zero now able to use camera modules, perhaps camera-based Pi projects like these digital binoculars or time-lapse camera rigs can now get even smaller.

[via Engadget]

Self-Driving Cars Get Tiny

May 16, 2016 by Bryan Cockfield 4 Comments

There’s a car race going on right now, but it’s not on any sort of race track. There’s a number of companies vying to get their prototype on the road first. [Anurag] has already completed the task, however, except his car and road are functional models.

While his car isn’t quite as involved as the Google self driving car, and it doesn’t have to deal with pedestrians and other active obstacles, it does use a computer and various sensors to make decisions about how to drive. A Raspberry Pi 2 takes the wheel in this build, taking input from a Pi camera and an ultrasonic distance sensor. The Pi communicates to another computer over WiFi, where a neural network operates to make decisions about how to drive the car. It also makes decisions based on a database of pictures of the track, so it has a point of reference to go by.

The video of the car in action is worth a look. It’s not perfect, but it’s quite an accomplishment for this type of project. The possibility that self-driving car models could drive around model sets like model railroad hobbyists create is intriguing. Of course, this isn’t [Anurag]’s first lap around the block. He’s already been featured for building a car that can drive based on hand gestures. We’re looking forward to when he can collide with model busses.

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Six Years Of Work And Rationale In A DIY Book Scanner Documented

April 29, 2016 by Gerrit Coetzee 6 Comments

[Daniel Reetz] spent six years working as a Disney engineer during the day and on his book scanner, the archivist at night. Some time last year, [Daniel] decided enough is enough, got married, and retired from the book scanner business. There’s a bit more to it than that, but before leaving he decided to dump, not just the design, but the entire rationale behind the design into a twenty-two thousand word document.

One of his big theses in this document, is his perceived failure of the open hardware movement. The licenses aren’t adequate, as they are based on copyright law that only applies to software. This makes it impossible to enforce in practice, which is why he released the entire design as public domain. He also feels that open hardware shares design, but not rationale. In his mind this is useless when encouraging improvement, and we tend to agree. In the end rationale is the useful thing, or the source code, behind a design that truly matters. So, putting his ~~money~~ time where his mouth is, he wrote down the rationale behind his scanner.

The rationale contains a lot of interesting things. At a first glance the book scanner almost seems a simple design, not the culmination of so much work. Though, once we began to read through his document, we began to understand why he made the choices he did. There’s so much to getting a good scan without destroying the book. For example, one needs a light that doesn’t lose any color information. It doesn’t have to be perfect, as the software can correct the white balance. However, it can’t lean too far away from the natural spectrum, it can’t be too bright, and it can’t be uneven, and it can’t be prohibitively expensive. A lot of thought went into the tent light design.

[Daniel]’s book scanners are immensely popular, and are being used all over the world. He’s certainly made an impact, and the community that formed around his project continues to grow without him. He made some interesting points, and if anything wrote a really good build and design log for the rest of us to learn from.