Whats the most affordable way to setup a large screen outdoors for live video My company produces some out door concerts that will have 15-18k people attend. I'd like to setup a video screen next to the stage that I can use to show a video feed of the concert. I don't have a lot to spend on it, but I would be reusing it for other things, so what do you think? I have a switcher that does hdmi and hd-sdi output, so a projector or system would need to use that. 

I'm trying to create something, similar to the picture attached.
"Most affordable" makes this a very difficult question to answer. The way most festivals do it is by hiring large screens. You could try and do it with a projector, which can work okay at night, but not so good in daylight (like a drive-in cinema). 

For bright displays there aren't really any shortcuts - 


Have a good video platform and desk
Route signal
Use good quality screens


Technology-wise, it is very simple, as you aren't doing anything clever with video.