Removing Things in Perspective
http://www.layersmag.com/design/objects_perspective.php

Kelby, Scott
Layers Magazine
2005

Abstract:

Before Photoshop CS2's introduction of the Vanishing Point filter, cloning away things in perspective was one of the hardest removal tasks of all. Luckily, this incredibly cool filter not only simplifies removing things in perspective, it actually makes it fun. In fact, this is one of those filters that's so amazing, you can wind up spending hours cloning away things that have no business being cloned away.