Run change detection process algorithm of FPE (which outputs a list of ids of citygml that changed ?) on two versions of the city (e.g. 2009 and 2012)
Edit the database to replace the citygml files that changed with the new ones (can be extracted from the citygml files with the ids from changedetection)
Update the dates of the citygml features in the database accordingly
Capture FDE know how on how to "temporalize" (associate temporality) CityGML data with change VCity's change detection algorithm.