Map layout, also called map composition or (cartographic) page layout, is the part of cartographic design that involves assembling various map elements on a page. This may include the map image itself, along with titles, legends, scale indicators, inset maps, and other elements. It follows principles similar to page layout in graphic design, such as balance, gestalt, and visual hierarchy. The term map composition is also used for the assembling of features and symbols within the map image itself, which can cause some confusion; these two processes share a few common design principles but are distinct procedures in practice. Similar principles of layout design apply to maps produced in a variety of media, from large format wall maps to illustrations in books to interactive web maps, although each medium has unique constraints and opportunities. While much of cartographic design is constrained by geographic reality (i.e., things are what they are and where they are), the cartographer has more freedom in layout than in designing the map image. Therefore, page layout has more in common with graphic design, with its own principles of layout, than any other aspect of cartography. Another impact of this relationship is that the cartography profession has largely adopted these principles, with relatively less unique research on the topic by academic cartographers than other aspects. The work of Rudolf Arnheim, especially his 1954 Art and visual perception, was especially influential during the formative years of academic cartography, and is still quoted as part of the canon in cartography textbooks. In practice, it is common in publishing teams for the layout portion to be executed by professional graphic designers, not cartographers. Some of the major design principles that are most applicable to map layout are: Attention flow: Map reading is a process, often a complex one, requiring the map user to glean information from the map, and make interpretations and judgments from that information.