1. A computer implemented method of fitting a plane for a three-dimensional model, the model comprising vertices interconnected by line segments, the plane and model being represented by data in computer memory, the method comprising: accessing: a collection of digital photos and a cloud of points, where the photos are of a real world scene, where the photos are three-dimensionally arranged in a three-dimensional space containing the three-dimensional model, where the points are also arranged in the three-dimensional space, and where each point in the cloud corresponds to a feature of the scene that exists in at least two of the photos; for each digital photo, for a given digital photo, computing and storing a vanishing direction specific to the given digital photo by analyzing the given digital photo to identify a corresponding vanishing point specific to the given digital photo, and using the vanishing point and the orientation of the given digital photo in the three-dimensional space to compute the vanishing direction specific to the given digital photo; receiving user input and according to the user input selecting, from among the first and second vanishing directions, the first vanishing direction; arranging the plane in the three-dimensional space by fitting the plane to at least the vanishing direction specific to the first digital photo and to at least one of the points in the plurality of points; and displaying a rendering of the model according to the fitted plane.