We do a lot of lifesize people cutouts for things like trade shows. We did this one for our good customer Peak Structural. They used it to show a celebrity endorser of their product without having to bring him to the show!
Generally, all we need is a good digital picture to give you a good looking lifesize people cutout. These days, your smart phone is taking a 12 megapixel image, which is plenty to get good results, as long as the photo is sharp and reasonably fills the screen.
Of course, you have to be careful that things fit reasonably within the 36×72″ envelope that we can ship. People cutouts with a hockey stick extended, for instance, are not a terribly good idea.