Final answer:
Illusionistic space in art creates the sense of depth on a flat surface. This is often achieved through linear perspective and a horizon line, although not all works feature a visible horizon, as seen in Eliasson's installation that challenges traditional perspectives.
Step-by-step explanation:
Illusionistic space in art refers to the technique of creating the impression of three-dimensionality on a two-dimensional surface. Artists utilize various methods like linear perspective, which involves a horizon line and vanishing points to create this effect. If a horizon line isn't visible, as might be the case with some artworks that do not adhere strictly to linear perspective, the implied line where the earth or sea meets the sky is typically at eye level of a standing observer.
Artists may intentionally alter scale and proportion within a work to convey particular effects. These variations can be consistent if the artist maintains the same system throughout the piece, but sometimes artists may deliberately use inconsistent scales for stylistic or symbolic reasons, such as to highlight importance, narrative elements, or to challenge traditional perspective as seen in the works of Picasso during the Cubist movement or Matisse's intentional disruption of linear perspective.
An example that breaks from traditional perspective is Olafur Eliasson's installation Inside the Horizon, which eschews a single horizon line. Instead, it invites viewers into an immersive environment filled with mirrored and yellow glass-clad columns of varying sizes and orientations that interact with light, producing a kaleidoscopic array of reflections and thus creating a dynamic spatial experience that challenges perceptions of horizon and space.