in sculpture, three-dimensional projection from a flat background. In alto-relievo, or high relief, the protrusion is great; basso-relievo, or bas-relief, protrudes only slightly; and mezzo-relievo is intermediate between the two. Ancient Egyptians and Etruscans also used cavo relievo, intaglio, or sunken relief, in which the design is incised deeper than the background. High relief, although also used in ancient times, reached its climax in the baroque period. Bas-relief is commonly employed on coins and on medals.
Image – Augustus Saint-Gaudens, Robert Gould Shaw and the 54th Regiment Memorial, 1897-1900, high relief* in patinated plaster, National Gallery, Washington, DC. The subject of this sculpture is also that of the 1989 movie Glory [link to a still from the movie] directed by Edward Zwick.