Page 254 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

Chapter 8: Field Photography 233
and most efficient manner. Photographic recording, which allows measure- ments to be taken and provides information about the site, is therefore a useful method of maximizing resources. However, the archaeologist must have a clear idea of what needs to be recorded and why, and must also be conversant with the techniques to be used and their limitations; at the same time the person taking the photographs must have a thorough understand- ing of what is needed by the archaeologist. The photographer can then implement any number of techniques to help in the production of prints and plans of the site; but unless the right photographs are taken in such a way that plans and measurements can be created from them, the process will be wasted. For this reason a great deal of thought needs to go into the planning of this type of recording work. It is easy to assume that photog- raphy is a panacea and all that is necessary to record the site is to take lots of photographs. It is important to carefully document the work, otherwise the result will be a great number of irrelevant photographs, and a lot of wasted time and effort trying to interpret them. Carefully prepared and placed scales, accurate positioning of the camera, and planning will help to produce a photograph that can then be used as an aid in plan-making.
There are a number of different types of technical photography: a general view, usually a low oblique, to show the site; a vertical to provide a simple plan of an area; a close-up of detail on the site; a photomosaic for an overall site plan; a stereophotograph for viewing the site in three dimensions; and a photogrammetric coverage to obtain accurate three- dimensional site measurements. These different techniques can be used, depending on the requirements and needs of the work.
In the early stage of producing a predisturbance site survey, a photomo- saic can be used to provide a detailed, medium-accuracy site plan. It is almost impossible to hand measure all the small details of a site that are not required at a high level of accuracy. The mosaic will contain most of the information and can be used in conjunction with a conventional tape survey (see Mosaics). The intelligent use of a combination of conventional and photographic techniques is ideal for this type of survey. Photography is also useful as a method of recording the progress of an excavation. A series of photographs of a grid square under excavation provides a record of the location of objects and their relative orientation and stratigraphy. In the case where detailed and accurate information is required, for example, of a hull structure, photography can be used to provide supplementary infor- mation should a mistake have occurred in recording or measurement. Unless there is a photograph, it can be almost impossible to resolve these types of problems. It is worth spending time and effort to get good photo- graphic coverage, and photogrammetric and stereophotographs are partic- ularly helpful.