As a result of the urbanization, croplands in China
decreased dramatically and that placed a lot of threats to
China’s food security. However, how many acres of land
are developed due to urban expansion? The answers to this
question are quite different between the official statistics
and those derived from remotely sensed data [21,38].
Urban areas can be observed from remotely sensed data
with a resolution better than 100 m, and results obtained
from remote sensing are more objective. Using such data
properly, we can avoid the subjectivity in and manipulation
by different levels of statistical bureaus. Here, we mainly
use human interpretation method to map all 663 cities in
China.