A method for ascertaining output data of a global navigation satellite system (GNSS) locating device based on GNSS satellite signals in a vehicle, includes a) receiving surroundings data from the surroundings of the vehicle, b) generating a surroundings model to describe the surroundings of the vehicle using the surroundings data received in step a), c) receiving GNSS satellite signals from GNSS satellites using a GNSS receiver, and d) ascertaining output data of the GNSS locating device from the GNSS satellite signals received in step a). The surroundings model generated in step b) is used to compensate for anomalies caused by the surroundings of the propagation of the GNSS satellite signals from the GNSS satellites to the GNSS receiver.