AERIAL PHOTOGRAPH

• Aerial photograph is the photograph of an area taken from air with a camera mounted on an aircraft.
• This image of the ground that is being photographed gets formed on the focal plane of the camera’s objective lens at which a sensitive film is placed.
• With the distribution of light and shade in a photograph along with certain other factors, the various items on the photograph can be identified.

Aerial photographs are classified into two types:

1. Vertical photographs.
2. Oblique photographs.

Vertical photographs: In a vertical photograph, it is required to keep the camera axis vertical i.e. parallel to the direction of gravity When the camera axis is perfectly vertical, the photoplane is parallel to the datum plane and the resulting photograph is truly vertical photograph. But it is very difficult to maintain the optical axis of camera truly vertical. This gives rise to tilted photographs.

• In a tilted photograph, the camera axis is unintentionally inclined to the vertical by an angle not exceeding 3°.

Oblique Photograph: In an oblique photograph, the camera axis is inclined intentionally to the vertical and the resulting photograph is called as oblique photograph.

• A limiting case of oblique photograph is the high-oblique photograph which contains the horizon while in a low-oblique photograph, the photograph does not contain the horizon.

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