So far, we are aware of one case law as to nudity on own property.

Even if the property is visible from outside

The County Court Dortmund argued, that a man, who tends to relax nude on his property after a sauna session in the garden, may continue to do so. A neighbour had filed a lawsuit against him and now rescinded his claim, after the court had suggested that because of the imminent rejection of the lawsuit.

Link to an article in Der Westen (in German)