Aerial Photography

Jan 12th, 2008 by admin

Viewing photographs which are taken from a good, unique point of view is one of the most fascinating things in the world of photography. It is about the taking of photographs of the ground from an elevated position. The term usually refers to images in which the camera is not supported by a ground-based structure. Cameras may be hand held or mounted on an airborne tool such as a balloon, an aircraft, a kite, a skydiver and other similar tools, and photographs may be taken by a photographer, triggered remotely or triggered automatically. Platforms for aerial photography could be fixed-wing aircraft, helicopters, balloons, blimps and dirigibles, rockets, kites, poles and skydivers.

The art of aerial photography was first developed by Nadar, a French airman back in 1858. During the Second World War, aerial photography found a niche in military operations. Aerial photographs were used in spying and in the assessment of the battle ground. These photographs provided updated and realistic impressions of the topography and current situation in a certain area.

Uses of Aerial Photographs

There are many conceived and actual uses for pictures which are taken from above. Aerial photographs are actually used in the construction of topographic maps, in cartography, planning land use, archeology, production of movies, espionage, environmental studies, commercial advertising and in other fields.

Photographs and other images of the Earth taken from the air and from space show a great deal about the planet’s landforms, vegetation, and resources. Aerial and satellite images, known as remotely sensed images, permit accurate mapping of land cover and make landscape features understandable on regional, continental, and even global scales. Transient phenomena, such as seasonal vegetation vigor and contaminant discharges, can be studied by comparing images acquired at different times.

Camera vs Satellite for Aerial Photography
Cameras of various types are used to take aerial photographs. Although cameras have also been carried on spacecraft such as the Space Shuttle, satellites more frequently use electronic scanners to record ground scenes in digital form. These sensors record reflected or emitted energy in the visible, near-infrared, and thermal-infrared portions of the spectrum. Satellite scanner data are commonly displayed as images whose colors resemble those of color-infrared aerial photographs, but the colors of a given image can be manipulated by computer to enhance landscape features. Although certain satellite images are distributed as photographic film or prints, they are more often distributed as digital products. Side-looking airborne radar (SLAR) instruments on aircraft or satellites generate their own energy, which is recorded on being reflected back to them from the ground. This eliminates problems associated with cloud cover and haze. The oblique angle of the “side-looking” instrument yields images that are especially useful in analyzing landforms.

Aerial Photograph Los Angeles, Calif., Aerial Photography color-infrared, August 1989 Golden Gate Bridge, San Francisco, Calif., aerial photograph color-infrared , August 1982

The use of technology has also crawled into the field of aerial photography. Advances in radio technology has allowed for the use of aircraft models which are controlled by radio in the conduct of low-altitude photography. This is mainly used in advertising for the real estate business. This is because manned aircrafts are not allowed to fly low altitudes in populated locations. This task can be done by these radio-controlled aircraft models and they do the job very well.

Public Domain
Aerial photographs are considered public domain, because the pictures are taken from aerial views which are considered public places.

There are many ways to view aerial photographs on-line. One of the most popular ones is the Google Earth by Google. Google Earth provides satellite imagery as well as aerial photos of the planet. You can actually use the service to be able to search for different places in a certain area such as parks, restaurants, schools and hotels. It can also be used to be able to track down the best routes for reaching a certain location. You can also view the aerial photographs in different angles by tilting and rotating them.

These are some basic things about aerial photography. If you are interested in learning more about this topic, you can browse through some basic materials at the local library or use the Internet to get more information about it.

Orthophotos
Orthophotos are aerial photographs or digital versions of Aerial photographs that have been “orthorectified” using ground elevations data to correct displacements caused by differences in terrain relief and camera tilt. The process gives an orthophoto the accuracy of a map. Because aerial photographs show the texture of the ground in much greater detail than do maps, orthophotos are useful for updating maps and for studying surface features not necessarily visible in maps. The USGS produces digital orthophotos for map revision and for computer analysis using geographic information systems. Coverage of the entire country in the digital products is in progress.

What is Orthorectified?
Orthorectified photography is vertical photography which has been corrected so that it is true to scale and distortion free.

Generally photography is described as “vertical” - meaning looking directly down from above - or “oblique” - such as you would see looking out from an aircraft window with the foreground in good detail, training off to the horizon.

Plateau Images takes vertical photography and then drapes this imagery over a 3D model of the earth (Digital Terrain Model - or DTM) to remove any distortions from the shape of the earth and any camera defects or aircraft movements. This image is then tied to accurate survey points on the earth so that the final photographs are able to be used to measure and scale features quite accurately with real world coordinates.

Orthorectified photographs are used for a multitude of applications including town planning, environmental studies, engineering works, farm management and so on.