Modern location practice is based on photo grammetric techniques. The parallel to traditional methods is striking; each contains the succeeding steps of area and route reconnaissance, preliminary survey, and final location.

• 现代定线测量工作以摄影测量法为基础，和传统测量法的相同之处是显而易见的，都包括这些连续的工作步骤:区域和线路踏勘，初测以及最后的定线。