Aerial Photography

Aerial photography is the acquisition of a vertical image with a specialize camera installed on board of an airplane, equipped for this type of work.

Airborne acquisitions are always performed in such a manner that two consecutive photographs have a side and forward overlap. These overlaps enable a three dimensional (3D) observation of the territory, with the help of a specialized tool. The optical phenomenon, which makes it possible to see in 3D, is called the stereoscopy.

Overlap

In order to obtain a three dimensional view of a covered territory, part of the photographed land on one image has to be also present on the next image, this is what is called overlap.

Stereoscopy

As the airplane flies, the photographed area, which is showed on two consecutive aerial photographs, that is the forward overlap, provides a view of the territory photographed at two different angles. When looking at this part of the photographs with the help of a specialize tool, such as the stereoscope, it is possible to view the landscape (relief) because it appears in three dimensions.

The raw image, as it is acquired on board the airplane, can be processed and printed on paper film or diapositive; and is then called an aerial photograph.

When the image is digitalized and corrected so as to eliminate the imprecision resulting from the airplane position in flight and the distortion due to the ground relief, it is called an orthophotograph. Every orthophotograph is georeferenced, which means that it has location geometrical properties identical to those of a map.