Table 1.

Basic information of data processing.

Number of photos: 15590	Aerial photo area: 5.0738 km2
Spatial reference: Xi'an 1980 coordinate system is zoned at 3 degrees, and the central meridian is 111	Elevation datum: geoid height
Control points: 9	Check points: 6
Connection points: 3.58424 million	Treatment time: 20 d19h