Community Photo Collections
CPC's are another name for internet photo sharing sites such as Flickr.
"With the recent rise in popularity of Internet photo sharing sites like Flickr and Google, community photo collections (CPCs) have emerged as a powerful new type of image dataset. For example, a search for “Notre Dame Paris” on Flickr yields more than 50,000 images showing the cathedral from myriad viewpoints and appearance conditions. This kind of data presents a singular opportunity: to reconstruct the world’s geometry using the largest known, most diverse, and largely untapped, multi-view stereo dataset ever assembled. What makes the dataset unusual is not only its size, but the fact tha it has been captured “in the wild”—not in the laboratory." (http://opendotdotdot.blogspot.com/2007/11/3d-digital-commons-as-metaphor.html)