Software supporting an artwork by Aaron Marx at the Minneapolis Public Service Building, 505 Fourth Avenue South, Minneapolis, Minnesota 55415
The artwork occupies the ceiling of an elevator lobby. It is constructed from wood slats, profiled to represent the topography of the Mississippi River as it flows through downtown Minneapolis. The slats are backlit with an array of LED lights which are animated using a Color Kinetics controller. The lighting animations are triggered, in real time, by the conditions of the Mississippi River.
The device that retrieves data from USGS Water Services and sends commands to the lighting controller is a Raspberry Pi 3b microcontroller. It is running the Ubuntu Core 20 operating system. This device connects to the internet via a WIFI network.
The microcontroller is running an program written in the F# programming language using the .NET software development platform. The source can be viewed on GitHub.
From this folder:
Build the console application:
dotnet publish RiverMonitor/ConsoleApp/ConsoleApp.fsproj -c Release -r linux-arm64 --self-contained true -p:PublishSingleFile=true -o app
Copy the built application from the build folder onto the Ubuntu server at /home/ubuntu/rivermonitor:
cp app/* /home/ubuntu
Copy the rivermonitor.service file onto the Ubuntu server at /etc/systemd/system/rivermonitor.service:
cp rivermonitor.service /etc/systemd/system/rivermonitor.service
Copy the 50-cloud-init.yaml file onto the Ubuntu server at /etc/netplan/50-cloud-init.yaml:
cp 50-cloud-init.yaml /etc/netplan/50-cloud-init.yaml
Start the service by issuing the command:
systemctl start rivermonitor
and ensure the service starts automatically on boot using the command:
systemctl enable rivermonitor
Overwrite the settings.json file in the application folder with test.json to test the system and live.json to retrieve live measurements from USGS. Reboot the server to see the changes take effect.
Real time Mississippi River data is retrieved from USGS Water Services. The reading of interest is discharge (parameter 00060), which is measured in cubic feet per second. The reading is produced by instruments at St. Paul (site 05331000). Many other parameters are available on the physical parameters page.
The query for retrieving the most recent measurements in JSON format is:
https://waterservices.usgs.gov/nwis/iv/?sites=05331000&period=P1D&format=json,1.1