Noun
a map drawn from observation (rather than from exact measurements) and representing the main features of an area
Source: WordNetNansen (1897), Vol. II p. 276 Whether this still-distant land was Franz Josef Land or a new discovery they did not know—they had only a rough sketch map to guide them. Source: Internet
Gygax: "Yes, I had a sketch map of the remainder of the globe.. Source: Internet