What is the main principle of a total station used in landfill surveying?

The main principle of a total station used in landfill surveying is to accurately determine the three-dimensional coordinates (horizontal distance, vertical distance, and elevation) of a target point by measuring angles and distances electronically. A total station combines an electronic distance meter (EDM) with an electronic theodolite (for measuring angles). The EDM emits an infrared or laser beam to a reflector placed at the target point and measures the distance based on the time it takes for the beam to travel to the reflector and back. Simultaneously, the theodolite measures the horizontal and vertical angles to the target point. The total station's internal computer then uses these measurements to calculate the X, Y, and Z coordinates of the target point relative to the instrument's position. This allows surveyors to quickly and accurately map the landfill's topography, calculate volumes of waste, and monitor settlement. The instrument needs to be set up over a point with known coordinates and properly leveled to ensure the accuracy of the measurements.