Why is 3D trilateration necessary for determining locations on Earth?

3D trilateration is essential for accurately determining locations on Earth primarily because it takes into account altitude. While 2D trilateration can provide a location on a flat surface using the distances from sources, such as satellites, it fails to consider the vertical component, which is critical for understanding a position in three-dimensional space.

In practical terms, when determining a location on Earth using satellite signals, especially for applications like GPS, the altitude or elevation is a significant factor that influences positioning. For instance, if only the horizontal position (latitude and longitude) is calculated without altitude, it could lead to inaccuracies when assessing a location in three-dimensional environments like mountains, valleys, or urban settings with tall buildings.

By employing 3D trilateration, the system effectively triangulates not just the flat coordinate system but includes height, ensuring a precise representation of where an object or point is located in the world. This capability is fundamental for various applications, including navigation, mapping, and geographic information systems, where accurate height information can alter the context of the data being utilized.