On-Site Aerial Photography

Introduction

Aerial photography ( 1 2 3 ) is an established technique in archaeology ( 1 2 3 4 5 6 7 8 9 ). Aerial photographs taken from both planes and satellites are readily available for download from the internet (e.g. 1 ). The limitation of such images is that they are taken at a given point in time which may not be the most appropriate for the intended application. For example, on an archaeological site, you may want to bring out surface features by taking shots when the sun is both strong and low in the sky, thereby casting strong shadows. On some sites, you many want to take photos when the soil is particularly dry, so that subsurface features can be delineated by changes in the colour of vegetation. Or, as in our case, you might also want to take a photograph of a familiar scene from a new perspective.

Ideally, you should be able to take your aerial photograph at the most appropriate time of day/season/year for your application. If expense is not a problem, and there are no flight restrictions in operation for the intended area, this can be done by hiring either a helicopter or plane and taking your own photos or you can commission your own survey. A cheaper alternative is to use model aircraft ( 1 2 3 4 5 6 7 ). Although cheaper, this approach may require some skill, depending on the aircraft of choice, and your equipment is always at risk of damage. However, with off-the-shelf systems (100k low resolution ) and cheap digital cameras, this is certainly a viable option and there are some very cost effective gyro stabilization solutions for the more serious photographers. A camera-on-a-stick (1 2 ) approach is also possible and has the advantage of not being as dependent on the weather conditions.

Birds have been used for aerial photography for over 100 years eg Bavarian Pigeon Corp (1) (2)

Rockets ( 1 2 3 4 ) are another possibility, but they can be a little erratic. Kites ( 1 2 3 4 5 6 7 8 9 UK Law) are more stable, but, like rockets, they require specific, if different, weather conditions.

Balloons are a stable choice ( 1 2 3 4 Early example), but they require relatively calm conditions. Helium balloons work well, but they are not necessarily the cheapest option. Hot air balloons appeal as a possible photographic platform as they are both cheap to buy/make and to fly. Many thanks to Thomas Taylor for his advice.

Kites will also be considered for use in weather conditions that are inappropriate for balloons (most of the time!).

Our first approach will be to use the camera's time-release setting to take a photo 10 seconds after launching. A wireless trigger , will then be the next option (see also 1 2 ). If you want to trigger a digital stills cameras with IR capability James Gentles has the solution.

The first (and probably the only) hot air balloon that we will try is ~6ft high with a circumference of ~18ft. This is about the smallest practical size of balloon for the smallest digital cameras (<100g). Helium balloons are, as far as we are concerned, too expensive to use routinely in a non-commercial context.

The first kite will be of conventional Rokkaku design (Apperley) with one 5 ft vertical strut and two 4 ft horizontal struts 3ft apart (= 16sq ft).