Three things from this week.
Raspberry Pis are showing up in stock more often. So I have to get to work and start building the next version of my Gamma Camera rig. I’ve been thinking about it for so long that I’m afraid of falling into second system syndrome. I guess it’d be seventh system syndrome in my case…
I’ve got a lot of half-complete thoughts about what I want to put into the next rig so here are three of my best ones. Maybe that only adds up to one and a half things from this week but c’est la vie.
The Raspberry Pi Global Shutter camera
There have been a couple new camera modules from the RPi foundation since I built gammacam P6: camera module V3, the M12 mount version of the HQ camera module, and the Global Shutter camera module. I’ve picked up a few of each module but I have yet to integrate one into a new build. The Global Shutter camera is made for machine vision applications so it seems like the obvious choice. The form factor is similar to the HQ but I will need to change up my camera head a little bit to accomodate the new PCB cover. The IMX296 sensor is only 1.6 megapixels at 60 fps compared to 8MP from the IMX219 in the HQ camera module. I like the separation of camera head and compute that I get from the HDMI extensions. Since the electrical connections are the same I should be able to reuse those parts.
More robust compute cage
My fascination with T-slot extruded aluminum persists. Specifically the 2020 profile with a 20mm x 20mm cross-section. The kits from MakerBeam in 10mm and 15mm sizes are cute but have fewer options. I really love seeing what people build with this stuff. I tried to produce a custom computer case for myself. That particular project went on for a few weeks before I paused it indefinitely. Still, I feel a deep need to build something real out of these parts.
In Gamma Camera, the compute cage holds all the Raspberry Pi modules, the router, and the batteries. I like my current build (P6) which uses 15mm rod from Small Rig but I know I’m stretching what the 15mm rod system is intended to do. So I’ll try some of my t-slot parts on the P7 build and see what I can do.
Flash drive storage
Finally, the microSD cards I use in the Raspberry Pi are apparently not very fast. I’ve done some benchmarking and I see the same thing that others have reported. There are inexpensive large thumb drives which give better performance for a lot of applications. On Gamma Camera we want to be able to write video or images to disk fast as possible. Or at least as fast as the camera module can produce them. Extra write bandwidth opens up support for higher resolutions, higher framerates, or multiple camera modules on a single Raspberry Pi. And it turns out that it’s really not difficult to boot from a flash drive. USB flash drives are even easier to deal with than microSD cards.
When will I get around to the next build? Soon. It really won’t be that different from what I’ve built previously. Each of the things I’ve outlined isn’t a big leap. The mechanical design will take me a while. Flash drives aren’t hard though and I have some research ready to publish. And with parts available I can order new components if I don’t want to take apart the current rig.
There are lots of other directions I want to explore but I want to keep balancing my time using the camera array against the time I spend building camera arrays. Other ideas I have are generally logged in the issue tracker and, of course, contributions are welcome.