If the artist intend art, but others considered it porn, which is it? Is it based on the opinion of the creator, or the beholder?
Both. Yes, by my definition it may be porn to one person, and not another. Hey, I've spoken to a person who found the Bible quite pornographic.
Porn has a certain... repetitive quality. If you show a given action once or twice, it may be art. If you show it repeated seven times, it becomes more pornographic.
I've often wondered about that with modern art: who says something is art?
The general public may find it hard to understand. The community of peers then. If enough fellow artists agree that it has creative value, then it indeed must.