The water smooth surface always attracted a look of the person. Beauty of the seas and oceans, rivers and lakes was sung by poets and prose writers, artists and photographers tried to imprint. On clear sunny day the blue of the sea is pleasing to the eye – whether but many know why water blue?

It is possible to define distance between two points, having measured length of a piece which is under construction between them. If coordinates of points are known, then the distance can be calculated, using mathematical formulas.

Often are guided by areas not only on parts of the world, but also in the direction on any given objects which are well traced visually and can effectively be used for orientation.

The distance is measured by means of various devices. Range finders, roulettes, rulers and other devices are applied to direct distances. It is possible to apply roller range finders (curvimeters) to measurement of any trajectories. Also distances can be counted if parameters of the motion of bodies overcoming these distances are known.