From the project State of the Municipal Map of Catalonia at a scale of 1: 5 000, the official information at the same scale (geometries and attributes) is extracted and from this they derive, for generalization, the rest of the scales.

The official reference scale is 1: 5 000. The geoinformation of the rest of the scales is generated from the simplification of the information contained in the scale immediately more big. So that, Administrative divisions at 1:50 000 scale are generated from the information compiled at 1: 5 000 scale, Administrative divisions at a scale of 1: 100 000 are generated from 1:50 000, Administrative divisions at a scale of 1: 250,000 are generated from 1: 100,000, and so on.

The simplification of linear entities in this case is done through generalization operations which, taking into account the purpose, scale, value and precision of the data to be obtained, removes certain bends and small intrusions / extrusions from a line, without destroying its essential shape but reducing precision.

The next step is to choose a suitable tolerance for the scale of representation of the administrative divisions. The tolerance value set determines the degree of simplification. The larger the tolerance value, the grosser the resulting geometry. With smaller tolerances, a more faithful geometry at the entrance is generated.

A different tolerance is applied to lines that define administrative boundaries that do not have coast classification and those that do. This difference in treatment between the lines that make up the coastline and the other lines is necessary due to the shortened nature of the coastline, which means that it is captured with many more points than the rest, since municipal lines in general are made up of straighter sections, and applying the same tolerance would make the result eliminate geometries such as small piers or shippers that need to be respected.

Finally, there is quality control of the errors that may have arisen during the process of simplification, such as line crossing, overlapping, or zero-length lines.

Within the generalization process, it is estimated to eliminate, on the coastline, the smallest polygons of the surface established for each representation scale (basically islands).