In the main points, I am definitely with Carodan on this.

I am intrigued by the comments about a camera obscura.   I think David Hockney wrote something on this a few years back and, as far as I recall, some of the response was fairly sceptical.   Back in 2001, there was a Vermeer exhibition in London and I was privileged to see what may be Vermeer's greatest picture, known in English as "The Art of Painting".   There is a rather small reproduction of it at

http://www.khm.at/homeE3.html 

(You then need to follow Picture Gallery ==> Holland: 17th century ==> Johannes Vermeer "van Delft".   You'll notice that the Vermeer is Vienna's prized exhibit.)

This picture contributes to the current debate in a somewhat double-edged way.    The text accompanying the picture at the Kunsthistorisches Museum Wien website (i.e. link above) states unequeqivocally that Vermeer employed the camera obscura technique.   I think I am right in saying, however, that Vermeer's studio still exists and that there is no way that it ever looked remotely like the studio he painted;  this was a wistful joke, illustrating his dream, but also a demonstration of his skill:  patrons who visited his studio, where "The Art of Painting" was, no doubt, prominently displayed, cannot have failed to have noted that Vermeer had painted the setting from his imagination.

Probably, the only thing in the picture that a prospective client would find, when visiting Vermeer's studio, was the artist himself (and you only see the artist from behind in the painting, so you can't be sure that it is he).  The would-be patron would not have seen the neatly tiled floor, the bright, natural illumination, the splendid curtains, or the chandelier.   I doubt if the artist would have been so finely attired, either, especially if he was expecting to do any actual painting.    He also probably didn't own the splendid map which appears in the background of "The Art of Painting".

On the other hand, everything in the final painting was entirely at home in the Netherlands of Vermeer's time and Vermeer will have seen it, even if he had to go to the property of someone more prosperous than he to do so:  tiles, luxurious curtains, maps and chandeliers, the fine clothes that those in less precarious livelihoods could show off.   "The Art of Painting" is a tour de force of the artistic imagination, but it also shows how even the greatest artists exploit props.   If a "purist" says that he or she created every last item in a picture from imagination, one is entitled to ask, "Why?"