While a topographic romance [q.v.] is an imaginary adventure set in a real landscape, a cartographic romance is an adventure story set in an imaginary landscape that has been developed in sufficient depth of atmosphere, detail, and consistency as to suggest exceptional commitment to it and imaginative involvement with it, on the part of the author, and which become accessible to readers. Tolkien's Middle-earth, particularly as depicted in its late Third Age, is an outstanding example; it has invited the efforts of later geographically-inclined contributors as Karen Wynn Fonstad's Atlas of Middle-earth and Barbara Strachey's Journeys of Frodo.
While a map or, better, series of maps is a necessity of a cartographic romance, it is not sufficient to make a romance truly cartographic. Perfunctory maps exist of Robert E. Howard's Hyborian world, but the Conan stories are marked by an improvisatory and ad hoc quality that prohibits their ever qualifying. Similar disqualifications apply to innumerable other works of fantasy and science fiction. The admitted subjective element in the previous paragraph's reference to "sufficient depth" means that disagreement about whether a given work qualifies or not, as cartographic romance, is likely, nay, invited. For example, are Ursula Le Guin's Earthsea books cartographic romances?