STEREOGRAPHIC PROJECTION OF THE HEAVENS OVER BELGRADE USED FOR THE CONSTRUCTION OF ASTRONOMICAL CITY CLOCK

摘要

There are many different ways of rendering 3D objects into two dimensions. Different kinds of projections areable to represent things like size, areas, distances or perspective, realistically. One particular kind of projection usedfor representing spheres and circles on spheres in two dimensions (i.e. some maps of the earth or celestial sphere) isstereographic projection. Stereographic projection has two important characteristics that differentiate it from otherkinds of projections: it preserves circles and angles. This paper discloses the construction of the stereographicprojection of the celestial sphere over Belgrade as the clock face of the astronomical clock. This astronomical clock willbe capable to present the motion, as seen from the Earth, of the Sun, Moon, Ecliptic and the phases of the Moon duringthe year. Moreover, the hours of the sunrise, noon and sunset will be clearly observed on the stereographic dial of theastronomical clock.