Aerial Photography has been around only for a couple of decades for civilian use, yet a couple more for military. It has ever since been in wide use for the facility it provides in understanding a landscape. This article will try to detail, through specific experience, the methods of aerial photography, rather than its use, which will be the topic of another article.
Besides aerial photography, the two other options for top-down photography available to us are satellite photography, and a manual photograph taken from on top of a truck- or tower-based high crane. Satellite photography –apart from Google Earth- is as of yet not cost-effective for us since producing high quality images on demand, costs unacceptably high, and the other option of photographing from a crane does not yield sufficient camera altitude for photogrametrical usability, so aerial photography is the most productive solution for us at the moment.
Being involved in finding top-down photography solutions for archaeological projects for several years now, I came across some different methods and options, which I will detail in the following paragraphs. Though some points on the source of the photography service are better made prior. The ideal solution for the source of service at first seems to be it being in-house. Though this brings some high initial cost and the additional cost of a dedicated staff. The service can also be possibly arranged by contacting local aviators and organizations to some degree involved in aviation as to book their flights if the desired work area is on or acceptably near their route. Renting an entire flight will obviously provide better freedom but this is in general more than ten times as costly. Lastly there happen to be prospecting aerial photography companies offering service with varying methods.
The first method we have used was renting a helicopter and boarding it to do the photography. While this is useful for wide area surveys through its ability to quickly change location, in general it is difficult to achieve the ideal position and especially altitude, since an unspecialized helicopter needs to tilt and lean to facilitate photography, and it has many altitude handicaps restricting to maneuver under a certain altitude. It obviously costs a lot. Another helicopter photography solution we found was boarding the regular patrols of the state forest ward or coast guard. While this is difficult to arrange and rather unfacilitating for our purpose, it cost us nothing.
Aerial photography companies, if they are available at the location of the project or are willing to travel (most are), seem to be the best solution to this need. Since in our location most archaeological expeditions are carried out in summer, aerial photographers usually take off in May and travel around to undertake their usually pre-booked work route. This, we found to be very cost effective and convenient, not to mention its availability on demand. Following their working methods have also provided us with some insight into how this can be done in-house.
The methods of aerial photographers vary greatly. While some prefer hiring helicopters to do mass photography of many different close-by projects, the ones we worked with generally used remote controlled cameras attached to various small-scale flyers. Of the remote flyers they used, the most efficient was a cable attached, unpropelled zeppelin about the size of a small car. It is controlled through moving the weight cart that it is attached to by a retractable cable several hundred feet long. The camera is attached to its underside mounted on a remote controlled rotatable platform. The camera itself is controlled by another remote apparatus with a viewing screen to catch the scene to photograph. The zeppelins stability and freedom of altitude provides great facility in shooting the desired scenes at the desired altitude.
Some aerial photographers prefer model aircraft to mount their camera on. While this seems to be a less costly investment, it would be advised to think well before investing in them since they generally don’t provide the freedom of the zeppelin-based camera and they tend to be not as stable as to be able to operate under wind. The maintenance of the model aircraft is also somewhat more complicated than a simple helium-filled zeppelin, since it has its own propulsion and remote control system.
All in all, while the methods of aerial photography may vary, the best suited for specific projects will probably be only determined through experience rather than suggestion. What have been shared in this article, as the reader must have observed are based on specific experience and must not be generalized. Therefore the prospecting archaeological projects are advised to think carefully and evaluate the options available to them and most importantly test the available systems through outhiring before investing into costly in-house arrangements.