Aerial Innovations in Mapping
In terms of precision, aerial surveys diminished the margin of error of a kind particular to ground triangulation. The margin of error in ground triangulation increased as topographers moved farther away from the three foundational points: the origin point at Huanxiling outside Xinjing (the capital of Manchukuo), the leveling origin point at the main traffic circle in Xinjing, and the tidal observation point at Huludao port on the Bohai Sea. For Inner Mongolia, located the farthest from the three foundational points, the margin of error with ground triangulation grew considerably.
In effect, ground triangulation could cause a potential cascade of error upon error down the ‘chains’ of a map. When the airplane itself became one of the three foundational points, it could hover above every unsurveyed site, rather than depend upon ‘chains’ of calculation derived from fixed landmarks.
Whereas triangulation by foot took months before a surveyor could draw up the terrain on paper, aerial surveys cut costs by 40 percent and the time by 75 percent, according to 1934 estimate from Belgium. The Manchuria Aviation Company claimed that in the “wilderness” of the Asian continent, both of these figures rose to 90 percent.
