A COMPARISON OF RECTIFIED PHOTOGRAPHY AND ORTHOPHOTOGRAPHY AS APPLIED TO HISTORIC FLOORS - WITH PARTICULAR REFERENCE TO

Historic floors which consist of mosaic or decorative tiles are often of high cultural or academic value, but by their very nature are vulnerable to decay and damage. On the other hand floors and footings are often the only surviving parts of a ruined building, especially in an archaeological context. They present particular conservation challenges and therefore often require a high quality metric record. The photographic recording of such floors has traditionally been undertaken using rectified photography methods. As most floors are relatively flat this is usually the most appropriate approach. The exponential increase in the power of personal computers during the late 20 th C and more recently the quality of digital camera technology has made digital rectification increasingly accessible to the non-professional surveyor. The less widespread technology of orthophotography (orthorectification using stereo-photography) can also be applied to historic floors and may be particularly appropriate for archaeological floors which have often suffered subsidence. This paper will compare the application of both methods to a Roman mosaic briefly revealed by an archaeological excavation at Croughton, Northamptonshire, UK in 2002. The practicalities and economics of fieldwork and processing methodologies will be examined. The resulting outputs will be compared for both quality and accuracy.