6 advantages of oblique aerial photographs over the vertical aerial photographs

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Oblique Aerial Photographs are Photographs taken at an angle.

If they are taken from a low angle earth surface–aircraft, they are called low oblique and photographs taken from a high angle are called high or steep oblique.

The technical definition of the vertical aerial photograph is photography looking down on a subject at an angle of less than or equal to three degrees from the vertical.

In other words, the vertical aerial photograph is defined as an aerial photography technique where the shots are taken from directly above the subject of the image

The following are advantages of oblique aerial photograph over vertical aerial photograph:

Oblique aerial photograph may use inexpensive cameras because they are not used for photogrametric or precision purpose.
Determination of feature elevations is more accurate using oblique aerial photograph than vertical aerial photograph.

An oblique aerial photograph covers more ground area than vertical aerial photograph taken from the same altitude and with the same focal length.
If an area is frequently covered by cloud layer, it may be too low and/or impossible to take aerial vertical photograph but there may be enough clearance for oblique coverage.
Oblique aerial photograph have more natural view because we are accustomed to seeing the ground features obliquely. For example tall objects such as bridges, building towers and others will be more recognizable because the silhouettes of these objects are visible .

Objects that are under tree or under other tall objects may not be visible on vertical aerial photograph if they are viewed from above. Also some objects such as ridges, cliffs, caves and others of the same reflection may not show on the vertical aerial photograph if they are directly beneath the camera.

Six (6) advantages of oblique aerial photograph over vertical aerial photograph

types of oblique aerial photography

low oblique aerial photograph

this is the photograph taken with the camera inclined about 30 degrees from the vertical.

it is used to study an area before before an attack, to substitute for reconnaissance, to substitute for a map or to supplement a map

characteristics of low oblique aerial photograph

it covers relatively small area ground
the ground area covered is a trapezoid, although the photograph is square or rectangular
the objects have a more familar view, comparable to viewing from the top of high hill or tall building
no scale is applicable to the entire photograph, and distance can not be measured. parallel lines on the ground are not parallel on this photograph; therefore direction can not be measured
relief is discernible but distorted
it doesnot show the horizon

high oblique aerial photograph

the high oblique aerial photograph is the photograph taken with the camera inclined about 60 degrees from the vertical.

it is used primarily in the making of aeronautical charts.

characteristics of high oblique aerial photograph

it covers a very large area as compared to ground or low oblique aerial photograph
the ground area covered is the trapezoid, but the photograph is square or rectangluar
the view varies from the very familiar to unfamiliar depending, on the height at which the photograph is taken
distance and directions are not measured on this photograph for the same reason that are not measured in low oblique aerial photograph
relief may be quite descernible but distorted just like in the low oblique aerial photograph. relief is not apparent in a high altitude
the horizon is always visible

what is trim trogan?

trim trogan is an assemblage of three photographs taken at the same time, one vertical aerial photograph and two high oblique aerial photographs, in a direction at right angle to the line of flight

the obliques photograph taken at an angle of 60 degrees from the vertical, side lap the vertical photograph, producing composites from horizon to horizon.