Geoid & Ellipsoid Brief Inroduction

What is the difference between geoid and elliptical?

Elliptics and geodesics are methods surveyors use to model the shape of the Earth. Although both types of models are used to create Earth models, there are fundamental differences. Elliptical models are more general in nature and do not take into account mountains and trenches. Elliptical and geographic pieces are complemented by a third type of model, topographical height.

Elliptic

Elliptical comes from the word "ellipse", which is simply circular. Ellips are generalizations of the balls. The Earth is not a real field, but an elliptical shape, because the Earth is slightly wider than length. Although there are other models, elliptical pieces are more suitable for the true shape of the Earth.

Geode

Like an elliptical, geode is a model of the Earth's surface. According to the University of Oklahoma, "geodes represent the surface of the Earth that will bear if the sea covers the Earth." This representation is also called the "surface of the equal potential of gravity" and mainly represents "mean sea level". The geode model is not an accurate representation of the sea surface. Dynamic effects, such as waves and tides, are excluded in the Earth model.

Topographic height

Topographic altitude (also known as "topographical altitude") is a more accurate model of the Earth than geode or elliptical. Surveyors measure ground height using satellite or aerial imagery. The altitude values ​​for this model are calculated relative to the mean sea level in different places on the planet.

The differences

Unlike geodes, the elliptical assumes that the Earth's surface is smooth. In addition, the planet is assumed to be completely homogeneous. If this is true, the Earth will not be able to obtain mountains or trenches. In addition, the mean sea level coincides with the elliptical surface. This is not true, however. The vertical distance between geode and elliptical exists as a result of geodesic observance of mountains and trenches as a model of the Earth. This difference is known as a "high geode". The differences between elliptical and geodesic can be significant, because elliptical is simply a baseline for measuring topographic altitude. The Earth's surface is supposed to be smooth, as the Earth is not.

USE

Icy and elliptical models are used in current global satellite positioning systems (GPS). GPS systems use the ellipse model as a basic line for measuring site height on the ground. However, some GPS systems now use a geoid model to better represent elevations. Precise measurements are most useful to surveyors whose job is to develop as accurate measurements of the Earth's surface as possible.