Buildings of a city change with time, new buildings are being built, existing ones are expanded and old buildings are torn down. Therefore the digital city model has to be updated regularly, typically every 2-3 years.
Depending on the data situation, we can offer different methods for updating:

• If the new, altered or torn down buildings have to be determined, we can do this in the course of an automatic "change detection".
• On the other hand, if the codes of the modified buildings are known, e.g. due to notices of the city administration, then we can model the affected buildings.

For building modeling we use automatic procedures or photogrammetry, depending on how the original city model was created. As a result of our update, we supply the current building models including the database commands for adding, changing or deleting the affected building units.