Communicating Between a Roborio and a Raspberry Pi

Hello, we are attempting to run vision processing on a webcam with python code run on a raspberry pi. However, we do not know how to actually send the data we get from the vision code to the roboRIO.
I’ve heard that there is a way to do it using smart dashboard but found no actual way to do it,

I would recommend using something based in ethernet. Network tables is probably one of the most common answers. We have done a plain old udp socket between the roboRIO and a Beaglebone Black in that past with good success.

NetworkTables is the way to go (SmartDashboard that you mentioned is a GUI that can be used to show information sent over NetworkTables).
However, if you’re using a Raspberry Pi, I highly recommend using the WPILib Raspberry Pi image which greatly simplifies many tasks included in vision processing.