A method is disclosed comprising: determining at least one relative altitude information based, at least in part, on at least one pressure information, wherein the at least one relative altitude information is indicative of a relative value of an altitude, determining at least one absolute altitude information associated with a data element of a database comprising map data, wherein the at least one absolute altitude information is indicative of an absolute value of an altitude, determining an estimation information based, at least in part, on the determined relative altitude information and,at least in part, on the determined absolute altitude information, wherein the estimation information represents an absolute value of an altitude. It is further disclosed an according apparatus, computer program and system.