Rephotography

Rephotography is the act of repeat photography of the same site, with a time lag between the two images; a "then and now" view of a particular area. Some are casual, usually taken from the same view point but without regard to season, lens coverage or framing. Some are very precise and involve a careful study of the original image.

Rephotography and photogrammetry in the sciences

Since the 1850s techniques were developed for surveying and scientific study, especially in systems (Paganini, 1880; Deville, 1889; Finsterwalder, 1890) of photogrammetry in which precise measurements made from triangulation of points in numbers of photographic records are made in order to track changes in ecological systems. Rephotography continues to be used by the scientific world to record incremental or cyclical events (of erosion, or glacier flow for example), or to measure the extent of sand banks in a river, or other phenomena which change slowly over time.

In social investigation

Rephotography has also been a useful visual method for researchers in sociology and communication to understand social change. Three main approaches are common - photographs of places, participants, or activities, functions, or processes – with scholars examining elements of continuity. This method is advantageous to studying social change due to the capacity of cameras to record scenes with greater completeness and speed, to document detailed complexities at a single time, and to capture images in an unobtrusive manner. Repeat photographs offer "subtle cues about the changing character of social life" (Reiger, 1996, p. 7). Upon analysis of elements of continuity within the images, researchers must be cautious to not make erroneous interpretations of change. Another closely related use of rephotography has been the political one made by Gustavo Germano in Argentina, who rephotographed family pictures of disappeared, thus making explicit both the missing people and the life that goes on.