It’s not unusual to create a large wall monitor using several monitors and graphic cards. But now with PiWall you can make a large wall monitor with only one Raspberry Pi per monitor, and a single master RPi to control the whole thing.
The PiWall software package makes it possible to build video walls of arbitrary size by combining a collection of screens, adding one Pi per screen to drive the relevant portion of the wall, and a master Pi to rule them all. We have been busy packaging and documenting a free version of the code and have now made this available on the website along with instructions about how to build your own PiWall.
As long as you have a few displays with an HDMI input, it’s easy to turn them into a large wall monitor. Simply plug one Pi per monitor into a network switch, have a Pi transmit a video to all the slaves RPi.