Aerial photography is the term used for photography that produces an image of an object, structure or place from an angle where the camera position is from above a person’s normal reach. This could be anywhere from 10 feet to 50,000 feet above the ground. Generally, there are eight different categories of aerial photography and two different methods within each category.
The first method within a category depends on whether the images are static (a picture taken by camera) or moving (a film or video taken by motion picture camera). A second method within each category depends on whether the camera is manned, i.e., having the photographer handle the camera directly, or unmanned where the photographer captures the image by remotely actuating the camera.
How the camera is elevated above the ground defines each of eight categories within aerial photography. These eight typical categories are:
o Fixed wing aircraft in low-level flight
o Blimps and powered airfoils
o Radio controlled fixed or rotary wing platforms
o High level mapping and surveying aircraft
o Satellite platforms looking back at the Earth (why this is not truly a category is explained below)
Each method has its own purposes, advantages and disadvantages.
Photographers use fixed wing aircraft in low-level flight to capture buildings and structures or to capture ground areas up to about a mile in diameter. This is because of the altitude above the ground an airplane can fly. FAA regulations restrict aircraft to stay at least 1000 feet above the ground in populated areas. Flying higher than 2000 feet for a photographic shoot is certainly possible but it may not be desirable because atmospheric conditions (haze) may interfere with the image quality. Photographs from low level, fixed wing flight can be either static images or moving images. The photographer usually holds the camera directly. An example of this application would be pictures taken to memorialize structures on the ground and their proximity to their surroundings. Another example would be to compare pictures of the same area taken over time in order to compare natural or man-made changes. The cost for fixed wing aerial photography is moderate in comparison to other methods. The most cost efficient method, per shoot, is to schedule multiple sites in the same area during the same flight.
Photographers use helicopters to shoot objects and structures that that fixed wing aircraft cannot. They often use a helicopter where it is important to follow a moving object or show motion over the ground. Photographs can be either static or moving and may be directly manned or remotely actuated from a mounted camera pod. An example of this application would be to capture pictures of buildings or landscaping from a continuous height where changes in the terrain make it impractical for an airplane to fly. The biggest drawback to using a helicopter to photograph the ground is the prohibitive cost of the aircraft, fuel, pilot and photographic crew. The big advantage to using a helicopter is that it can hover, follow ground terrain and follow moving objects.
Photographers occasionally use balloons for photography by tethering them over an event or area. Photographs are usually static and used to show action or short-term changes within a smaller area. Whether the photography is manned or unmanned depends upon whether the balloon is large enough to carry a pilot and photographer. An example might be a hot air balloon tethered over an event to capture pictures of the crowds and activities below. Photographers sometimes use manned balloons to photograph the ground but they are not usually the platform of choice because balloons travel with the wind direction and require calm wind conditions.
Photographers use blimps and powered airfoils at low speed and at low altitudes to capture an event or area. They may track something over the ground at lower altitudes where a fixed wing aircraft engine or helicopter would interfere with the target or would be dangerous or obtrusive. One example is the blimp that flies over a football stadium during a bowl game to photograph the event and provide television coverage. Another example is using powered airfoils to photograph animal migrations because the aircraft can fly fairly low and slow without making much noise. Photographers generally use blimps and powered airfoils for photographing events under specialized conditions.
Radio controlled fixed or rotary wing platforms can be further sub-categorized into military and civilian applications. The military operates sophisticated fixed wing drones over long distances for surveillance and tracking. These are large, remotely piloted aircraft. Their civilian counterparts are by comparison much less sophisticated and much smaller. There are specialty companies that operate mid-sized (in terms of payload capability) rotary wing platforms (camera carrying helicopters) often for surveying pipelines in remote and rugged terrain. A more typical civilian application used is on the scale of a robust radio controlled model helicopter with a remotely actuated, hand-held size camera. This application is somewhat economical but limited by how high the platform can fly. It requires very calm wing conditions.
Photographers sometimes use kites to loft smaller cameras for a unique low level, very localized view of the ground. A string or wire remotely actuates the camera. The photographer gets only a rough indication of where the camera lens is pointing so it is not a very precise method. This may be the least expensive way to capture a picture (unless the kite and camera crash) but it is not typically used in commercial applications.
Photographers use collapsible masts to elevate smaller cameras above the ground to obtain very low level, localized and remotely actuated images of the ground or a structure. It is possible to use this method with a video link that allows the photographer to aim the camera more precisely. Masts extend a camera from 30 feet up to 100 feet above the ground and require vehicle access. The cost of using a mast to gain elevation above the ground is generally lower than using an airplane if compared on a single location-by-location basis if the area is small. A van or trailer transports the mast. The photographer then erects the mast at each site. However, an airplane can capture multiple sites much more efficiently, saving equipment and crew time.
Fixed wing aircraft carry out high level mapping and surveying using sophisticated, highly calibrated mounted cameras that capture a continuous swath of ground. These images are from a height of 3000 feet to as high as 50,000 feet above the surface. This method is used for precise mapping, often over remote areas. Surveying aircraft can also be fitted with sensitive instruments like ground penetrating radar or magnetic resonance sensors to survey sub-surface characteristics. This is generally the most expensive and most sophisticated use of aerial photographic technology.
Satellite platforms looking back at the Earth could technically be categorized as “above the ground,” but are really in a separate category because of their height above the surface (the scale of their images) and because of military restrictions on the resolution that can be used by the civilian public. Satellite imagery is a completely different application. Satellite photography has an important role to play under specific circumstances but it is not currently a true substitute for civilian and scientific aerial photography.
Article Source: EzineArticles – George Murray