The word diorama can refer either to a nineteenth century mobile theatre device, or, in modern usage, a three-dimensional model, usually enclosed in a glass showcase for a museum.
The size of the proscenium was wide by high (7.3 meters x 6.4 meters). Each scene was hand-painted on linen, which was made transparent in selected areas. A series of these multi-layered, linen panels were arranged in a deep, truncated tunnel, then illuminated by sunlight re-directed via skylights, screens, shutters, and colored blinds. Depending on the direction and intensity of the skillfully manipulated light, the scene would appear to change. The effect was so subtle and finely rendered that both critics and the public were astounded, believing they were looking at a natural scene.
The inventor and proprietor of the Diorama was Louis Jacques Mandé Daguerre (1787–1851), formerly a decorator, manufacturer of mirrors, painter of Panoramas, and masterly designer and painter of theatrical stage illusions. Daguerre would later co-invent the daguerreotype, the first widely used method of photography.
Daguerre opened a second Diorama in Regent's Park in London in 1823, a year after the debut of his Paris original. The show was a popular sensation, and spawned immediate imitations. English artists like Clarkson Stanfield and David Roberts produced ever-more elaborate dioramas through the 1830s; sound effects and even living performers were added. Some "typical diorama effects included moonlit nights, winter snow turning into a summer meadow, rainbows after a storm, illuminated fountains," waterfalls, thunder and lightning, and ringing bells.
Painters of the Romantic era like John Martin and Francis Danby were influenced to create large and highly dramatic pictures by the sensational dioramas and panoramas of their day. In one case, the connection between life and diorama art became intensely circular. On 1 February 1829, John Martin's brother Jonathan, known as "Mad Martin," set fire to the roof of York Minster. Clarkson Stanfield created a diorama re-enactment of the event, which premiered on 20 April of the same year; it employed a "safe fire" via chemical reaction as a special effect. On 27 May, the "safe" fire proved to be less safe than planned: it set a real fire in the painted cloths of the imitation fire, which burned down the theater and all of its dioramas.
Nonetheless, dioramas remained popular in England, Scotland, and Ireland through most of the nineteenth century, lasting until 1880.
A small scale version of the diorama called the Polyrama Panoptique could display images in the home. and was marketed from the 1820s. A diorama painted by Daguerre is currently housed in the church of the French town Bry-sur-Marne, where he lived and died.
The current, popular understanding of the term “diorama” denotes a partially three-dimensional, full-size replica or scale model of a landscape typically showing historical events, nature scenes or cityscapes, for purposes of education or entertainment. Frank M. Chapman, a curator at the American Museum of Natural History during the late nineteenth and early twentieth centuries, helped popularize the style commonly seen today.
Modern museum dioramas may be seen in most major natural history museums. Typically, these displays use a tilted plane to represent what would otherwise be a level surface, a painted background of distant objects, and often employ false perspective, carefully modifying the scale of objects placed on the plane to reinforce the illusion through depth perception of viewing a larger space—representations of objects (of identical real-world size) placed further from the observer are smaller than those closer. Often the distant painted background or sky will be painted upon a continuous curved surface so that the viewer is not distracted by corners, seams, or edges. All of these techniques are means of presenting a realistic view of a large scene in a compact space. A photograph or single-eye view of such a diorama can be especially convincing since in this case there is no distraction by the binocular perception of depth.
Miniature dioramas, usually made in a shoe box, are used to represent scenes from historic events (e.g., tin soldiers arranged in a display depicting a famous battle). A typical example of this type are the dioramas to be seen at the Norges Hjemmefrontmuseum (Norwegian Resistance Museum) in Oslo, Norway.
Room boxes and other doll housing can also be considered dioramas. So too, the landscapes built around model railways, although they often have to compromise scale accuracy for better operating characteristics.
One of the largest Dioramas ever created was a model of the entire state of California built for the Panama-Pacific International Exposition and that for a long time was installed in San Francisco's Ferry Building.