From the Guardian:
Robert Kilp, the head of the city’s public affairs department, said if a journalist was caught filming in the area the tape would be removed and a warning issued, but if he or she was caught a second time the consequences would be more serious.
“The second time we will be really angry. This zone is owned by the city of Cologne and is not considered a public street,” Mr Kilp said.
“Anyone filming or taking pictures there will be liable to prosecution. Prostitutes are having sexual intercourse in cars there, it is not a good thing to be filming.”
Here.