Vertical Reference Frame

A vertical reference frame is a standardized way of defining "up" and "down" for measuring heights and elevations on Earth. It provides a consistent point of reference, typically based on the direction of gravity, so that measurements like sea level and land elevation are comparable across different locations. This system helps us accurately determine how high or low a point is relative to a fixed baseline, ensuring uniformity in activities such as mapping, construction, and navigation. Essentially, it’s a common "vertical coordinate system" that aligns measurements with Earth's gravitational pull.