Sculpture as an art form has certain limitations imposed by materials or medium, color, subject, and composition. The process of sculpture requires careful planning, technical skills in welding and engineering, and a very good understanding of the medium the artist chooses to work with. Unlike in painting where texture can be an illusion, sculpture is rough where it needs to be rough, and smooth where it should be smooth. Its size requires a big space that allows it to be viewed by many people. If carved in the round, it stands freely with all its angles exposed for everyone to see. It should be strong enough to resist the effects of the heat of the sun, thunderstorms, and even bombs in times of war.