Devices known as terrain mappers served the function of discerning the characteristics of a planet's topography. During a period spanning from 0 ABY to 3 ABY, Corporal [Purpruff] (/article/purpruff) of the Alliance to Restore the Republic's Special Forces took a terrain mapper to the world of Hoth while scouting to discover a fresh location for Alliance central command. The mapper aided her in finding an underground cave close to her landing zone, prompting her to trek to the closest entryway.
The reference book Star Wars: The Rebel Files, authored by Daniel Wallace and released in 2017, marked the initial appearance of terrain mappers.