ZHANG, Ruda December 30, 2018:  Use dollar style math markup. [1b7036c]
ZHANG, Ruda December 30, 2018:  More satellite imagery open data; Google Maps Plus Code. [7198f37]
ZHANG, Ruda December 10, 2018:  More on Google Maps API; Add newline before list [03f47c7]
Ruda Zhang January 08, 2017:  minor edits. [d5fddc1]
Ruda Zhang January 08, 2017:  More details on Ground Truth [9612f5e]
Ruda Zhang January 08, 2017:  Add new page to Category. [b590935]
Ruda Zhang January 08, 2017:  Add Google Maps: data and API [d14f24b]