If you zoom all the way in, you can see that they're pretty likely to be 3d-rendered (look at the slight breaks in the curve of the orange wall around http://j.

If you zoom all the way in, you can see that they're pretty likely to be 3d-rendered (look at the slight breaks in the curve of the orange wall around http://j.map.baidu.com/nA2e http://j.map.baidu.com/nA2e for example), not hand drawn like pixel art. Nevertheless, an amazing amount of work.