Method and localization system for setting up or updating an environment map

A method is described for setting up or updating an environment map and for ascertaining a position within the environment map based on a scan of an environment using electromagnetic radiation, in which environment data is ascertained by scanning the environment with the aid of at least one localization system using electromagnetic radiation, data pertaining to at least one wireless communications unit are collected by the at least one localization system, the ascertained environment data are allocated to at least one position or to at least one section of the environment map, and the collected data of the at least one wireless communications unit are used by an internal control unit or an external control unit of the localization system for plausibilizing the at least one position or the at least one section of the environment map of the ascertained environment data. In addition, a localization system is described.