Chinese google map baidu map can check the real time population density of cities in china,it just update every minutes.
not only big cities but some of small towns.
but it based on the location of baidu users (most people ) so it dosent works in hongkong where most people use google maps .
this is an example in a morning of a holiday
1
The most dense city shows in the map is not Shanghai but central guangzhou .
http://imgsrc.baidu.com/forum/pic/it...fbfaed045c.jpg
2
the density of beijing is lower than other major cities but the downtown area is the biggest in china
http://imgsrc.baidu.com/forum/pic/it...292cf57846.jpg
3
density of Tianjin is so low that many people are counfusing the population of it.
http://imgsrc.baidu.com/forum/pic/it...64024f1afe.jpg