Final answer:
Surveying is the technique used for determining 3D positions and measurements using baselines, parallax, triangulation, and trigonometry.
Step-by-step explanation:
The general technique of determining three-dimensional positions of points, and the distance and angles between them, is called surveying. This process includes setting up a baseline—a fixed reference line—and using the concept of parallax to measure angles from different vantage points. For example, a surveyor can determine the width of a river by establishing a baseline along the riverbank, sighting an angle to a tree on the opposite bank, and using trigonometry and the principles of triangulation to calculate the distance to the tree. This technique is not only essential for surveying land but is also used in creating 3D seismic surveys for exploring geological features.