Underground surveying is the process of survey operations performed underground in connections with tunnelling, exploration and constructions in subterranean passageways. An underground survey is quite different from the usual surface surveys as the process requires different tools and methods in order to complete.
On the other hand, open pit surveying uses aerial photography tools such as LiDAR and aerial triangulation to analyse a property from the air. The process creates fast and efficient results without degrading accuracy. This is to have a three-dimensional image of the mine that can help surveyors measure the surface and delegate accurate data from the images their tools have captured.