These sketches are done by Joel, whom I had the pleasure to work and hang out with in Funcom while he was Art Director on The Secret World. On a few occasions, both in Beijing and Montreal, we have sat and sketched together. These first ones are from the bar of Hotel Crown Plaza in Beijing.
Joel does such observation sketches with a black Sharpie, if I remember correctly – though on the one below from McGill University I think I can see some areas where he quickly borrowed one of my Copics.
He has a good eye for where to mark the transition from light to shadow, something that is always tricky when working only with a black / white contrast. James Gurney has a good post on that here.
Joel is now Associate Art Director for EA in Gothenburg, and he still seems to put things up on his portfolio site, so head over and have a look!