The National Maps Series at the scales from 1:25 000 to 1:1 million are revised in a regular cycle of six years. The contents of the maps are based on the current geodata from the topographical landscape model which shows the surface of the terrain with its artificial or natural coverage. Place names and the identification of objects are also included.
The topographic maps serve as the basis for representing a particular geographic topic (e.g. network of hiking trails, geology). The information pertaining to the topic is gathered and edited by in-house or external specialists.
The revision material (stereoscopic analysis, object catalogue, lettering) is assimilated into the existing map image. In other words, the material is chosen with respect to the scale, and is generalized and represented as authentically and legibly as possible. Names and indications which have disappeared must be entirely deleted and new ones written correctly and attributed unequivocally to the object. The production process takes approximately two years from the time the aerial photograph are taken (status of the map content) up to the publication of the printed map or the production of the digital pixel map.
The material is revised and adapted to an optimal cartographic representation for a particular topic. The representation and its implication must be unambiguous, clearly identifiable and graphically correct.
The map originals are produced with the aid of a CAD system. Furthermore, a geographic information system (GIS) has been introduced for the production process. The result is a digital raster dataset with a resolution of 50 lines per mm which serves as the basis for publication. The graphic data center then produces print originals and two different pixel maps at resolutions of 10 and 20 lines per mm which can be used by clients for customized digital applications and for various internal and external applications (e.g. interactive map applications, Internet, etc.). Finally, the in-house printing shop produces true-color and true-fitting maps using the polychrome offset method.
The maps are published in analog format as a printed map and in digital format as pixel maps. The pixel maps serve as the basis for interactive map applications such as Swiss Map and the Atlas of Switzerland.