Photographs used as part of research differ markedly from photographs used as illustration. The empirical value of photographic research requires the images to be obtained through a methodological process indexed to recognizable objects and spatial variables. The planner uses research-framed photographic images like a physicist uses mathematical calculations—to provide the visual evidence of systematic knowledge in relation to a particular planning problem. Photographic investigations also allows to capture complex situations with the click of a shutter. J. Collier and M. Collier help planners conceptualize this line of exploration by identifying three broad genres of visually based investigations that cover the most common photographic research situations: Mapping and survey, cultural inventories and documentation of social process, and counting and measuring. Planners use photographic research to document cultural inventories and social processes infrequently, mainly because of the amount of time it takes to develop a relationship with the research subjects necessary to be able to capture this type of image.