Dome

A dome is a doubly curved roof that covers a square, octagonal or circular space and behaves in section like an arch. Because its shape lets it carry load almost entirely in compression, it allows large spans in stone, brick or unreinforced concrete, materials that are weak in tension. The concrete dome of the Pantheon in Rome, open at its centre, and the dome of Hagia Sophia in Istanbul are among the best-known examples in architectural history.

How a dome sits on a building

Setting a round dome over a square room is an old geometric problem. Pendentives and squinches in the corners make the transition, sometimes with a drum, a cylindrical wall pierced with windows, placed in between. At its base a dome pushes outwards, and that thrust has to be taken by thick walls, buttresses, semi-domes or a tension ring. Contemporary domes are more often steel gridshells, timber shells or thin concrete shells, turning the form into a much lighter enclosure.

Modelling and rendering a dome

A dome brings daylight down into a space softly and from above. To capture that in a render, pay attention to how light from the drum windows spreads across the inner surface. On the modelling side, segment count matters: a dome built with too few polygons looks faceted in close-ups and quietly breaks the sense of scale.