Geopositioning

Geographic positions may also be expressed indirectly, as a distance in linear referencing or as a bearing and range from a known landmark.

In practice, observations are subject to errors resulting from various physical and atmospheric factors that influence the measurement of distances and angles.

These measurements could be made visually using a hand bearing compass, or in case of poor visibility, electronically using radar or radio direction finding.

The navigator will have more confidence in a position fix that is formed by a small cocked hat with angles close to those of an equilateral triangle.

To minimize the error, electronic navigation systems generally use more than three reference points to compute a position fix to increase the data redundancy.

As more redundant reference points are added, the position fix becomes more accurate and the area of the resulting error ellipse decreases.

Combining multiple observations to compute a position fix is equivalent to solving a system of linear equations.

Navigation systems use regression algorithms such as least squares in order to compute a position fix in 3D space.