'District 9', 'Elysium' and 'Chappie' were all born out of some visual concept first. 'Chappie' is the imagery, because I think I'm a visual person first, of this ridiculous robot character. It's much more comedy based and in an unusual setting.
I think that 'Elysium' the movie is unrealistic, with the space station and everything. I think 'Elysium' the metaphor is completely realistic: it's exactly where we're going.