Computer Code

Raspberry Pi Microscope Camera

Brine shrimp icon

My Raspberry Pi - based microscope camera uses the high-quality Raspi camera that was released in early 2020. It features a 12.3 megapixel Sony IMX477 sensor, with a pixel size of 1.55μm × 1.55μm, which is twice the pixel area than the previous Raspberry Pi camera model. The image quality is much better than the previous Raspi camera models, or the old AmScope 3 MP USP camera (MU300) I had been using before.

Slack notifications from scripts

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I find Slack extremely useful for collaborating with a team. It's also great for quickly and easily getting notifications about the status of a script that's running on a remote computer somewhere. In my case, I'm running bioinformatics pipelines that take hours or days to run. Slack notifications tell me when programs finish running, or if something odd has happened.

Below are two code snippets I've found useful:

Timelapse with time stamp overlay


Timelapse video of a house demolition with a time-stamp overlay

Sadly, our neighbors sold their house and it was recently demolished to make way for two new buildings. On the plus side, this gave me an opportunity to try out my Raspberry Pi camera and make a time lapse movie of the process. Specifically, I wanted to try a quick-and-easy way to add a time-stamp in the corner of the video to give an indication of the current time of the day.

Real-time speed estimation of cars with OpenCV

Little car icon

A short description of a program for tracking vehicles written in C++ using the OpenCV library. The goal is to count cars and collect statistics of estimated vehicle speeds. An adaptive background segmenter (MOG) and a perspective transform are used to pre-condition the video frames. If contours are found, their coordinates are fed to a Tracker class, which employs a Kalman filter and an assignment algorithm to keep vehicle identities straight.

Auto-restart Raspberry Pi when its target server is not reachable

Raspberry Pi logo

My security camera has been running great for months. Issues have arisen only when the wireless router gets restarted or the wireless connection gets lost for some other reason. The problem is that the Raspberry Pi doesn't automatically reconnect after a wlan connection is dropped. Here's a possible solution to the problem that doesn't involve unplugging the RPi.

Installing SASS and compass on Mac 10.11 (El Capitan) with MacPorts

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SASS/Compass with MacPorts on El Capitan. This is mostly a note to myself

When updating to El Capitan, my compass and sass installations had disappeared once again. But when I tried to just install the compass and sass gems with the system's build-in Ruby, I got a bunch of error messages like the ones shown here: