I use my line scan camera to take cool pictures of trains and other stuff.

For more information about how it works and the algorithms I use to process the images, see: line scan camera image processing.

But heretofore I had to plug it into my laptop, which was kinda annoying for many reasons.

• I have to carry a laptop around
• The Macbook Air I was using has only a 256GB SSD which necessitates bringing an external SSD
• On the Macbook Air, there were some bugs with sometimes the camera negotiating only a 480 MB/s USB2 link instead of the 5 Gbps one, leading to dropped frames
• It just doesn’t look cool and stylish like a custom made standalone camera
• Screen isn’t bright enough

1 The camera

OK here it is!

Here are slightly older pics with worse 3D printed battery holder, bezel, and no wifi hat.

1.1 Bill of materials

Here’s the BOM (prices are approximate):

1.2 Case design

I modelled the case in Rhinoceros 3D.

I ordered it from JLC CNC for about RMB 831, which is like $110.

1.3 Setting up the Jetson

I picked the Jetson because it has low price and great compute compared to the similarly priced Raspberry Pi 5.

I wanted to only use the NVME M2 2280, and apparently the only way to do so is to use the NVIDIA SDK Manager, which requires a x86_64 Ubuntu 24.04 machine. It was really annoying. I couldn’t do it from my Arch Linux machine (must be Ubuntu), another Jetson (not x86), or my Windows machine, but was eventually able to do it by actually using a Ubuntu desktop. The process was also really finicky with its USB cable requirements. I had to plug in the cable in the back of the PC.

Another unanticipated issue was that the Jetson doesn’t keep time when powered off due to not having an RTC battery. Sometimes, my photos end up being out of order.

Actually, you can just bridge R560 with solder. Some people online painstakingly solder a 560 mΩ SMD resistor which is super difficult. I think the actual resistance is supposed to be 1 kΩ and the “R560” is just the name of the part and not the resistance.

1.4 Touchscreen

The good news is that the touchscreen is super bright (2000 nits), so it is easily legible in daylight unlike the Macbook.

Also, it is powered by 5V USB (you can also power it by a barrel plug if you want), so I could just plug it into the Jetson and it just works.

1.5 Capture UI

It’s implemented in C++ with Dear Imgui.

GitHub code

I set up a systemd thing to launch it automatically upon boot.

I set up a keybinding to toggle capture on/off with the spacebar so that I can control it wirelessly with a Bluetooth macro pad, to avoid shaking the camera when capturing.

2 Future ideas

I’d do these differently next time:

• Add screw threads to the CNC case
• My wifi hat protrudes weirdly because my screws aren’t long enough and again, no screw threads. So I had to use standoffs.

Another idea is to add a regular video camera (i.e. an area-scan camera) to the thing. That would help measure the speed of the train as well as help me see which part of the scene the line scan camera is looking at.

Right now, the tripod quick release plate (a Peak Design plate) is attached by a single M4 screw. I’d like to use two screws instead attached to the Alkeria camera for better strength.

3 Other people's line scan cameras

3.1 Adam Magyar

Adam Magyar and his “Einstein’s Camera” is perhaps the most famous one.

His monochrome line scan camera takes really clean images even in low light, but is huge and needs a backpack. To be fair, it was over a decade ago.

3.2 Seth Itow

My former colleague Seth created his handheld battery-powered line scan camera independently after being inspired by my previous stuff.

4 FAQ

Do you actually carry it with a strap attached to those Peak Design anchor links?

Good heavens no! It’s just a meme.

What lenses do you use?

In customizing my line scan camera I mentioned that I converted it to Sony E mount (manual only, no electronic contacts).

I use a Cheecar 50mm f/1.2 and a Samyang 85mm f/1.8 CS, both manual focus for Sony E mount (APS-C). The line is 28mm long so an APS-C lens covers it while being affordable.

I also have a variety of full frame lenses that I occasionally use on both this and my Fuji GFX camera, including:

• Voigtlander Ultron 35mm f/1.7
• Voigtlander Apo Skopar 90mm f/2.8
• Voigtlander Apo Lanthar 125mm f/2.5

My Cheecar and Samyang have a IR-block filter, but the Voigtlanders don’t. Actually, I had one for the 90mm, but I smashed it accidentally.

How long does the battery last?

The Anker battery lasts about 1 hour. It is nice because it has a display indicating the amount of charge remaining, and it has a built-in USB-C cable capable of outputting PD 20 V and more than the 35 W needed for the setup.