This small team of photo interpreters was trained in photogrammetry the science of determining measurements from photographs.

这一小群摄解译人员受过摄学的训练，这是一门从照片中定值的科学。

Fast forward to the 1950s, and surveyors got a bit of help from photogrammetry, detailed photos taken from the air that they could use to measure heights and distances.

时间很快来到20世纪50年代，员们从摄学中得到了一些帮助，他们可以用从空中拍摄的高清照片来高度和距离。