Guides Types of Aerial Images

Types of Aerial Images

Aerial photographs are generally classified as being vertical or oblique. A vertical photograph has been taken with the camera pointing straight down toward the ground. An oblique photograph has been taken with the camera directed at an angle to the ground. Occasionally, aerial collections contain a small number of photographs taken on the ground when testing the camera before flight.

A greyscale drawing of a plane flying above 6 trees. A triangle pointing straight down from the plane indicates the area covered by a vertical aerial photo. A triangle pointing down at an angle indicates the area covered by an oblique aerial photo.

Vertical

Vertical photographs are the most common type of aerial survey imagery. When scaled, objects and distances can be measured with great accuracy, which aids in their identification. Survey imagery is taken with a 60% overlap between each image along the line of flight, allowing them to be viewed in three dimensions thanks to the principle of stereoscopic viewing. Stereoscopy allows photographic interpreters to gain further information about the height of landmarks and buildings. 

Vertical perspective photographs can provide useful information when used alongside mapping and other topographic resources. The detailed vertical photographs provided by National Collection of Aerial photography (NCAP) are used in the search for unexploded ordnance, in police investigations and the assessment of property boundaries.

A colour aerial photo of a broad, winding river. The river is dark brown and passes between green fields. An island sits in a particularly wide part of the river. A village is visible at the centre left edge, and a town is in the top right corner.

Oblique

Oblique aerial photographs provide the viewer with a more readily understood image of a location. They are useful for looking at foreground building frontages and geographic features. These types of images are taken with cameras fitted either in the nose or fuselage of a plane. Oblique photographs are classed as ‘high’ – which include the horizon – or ‘low’, which only show the ground.

The image below is a low oblique aerial photograph showing the same part of the River Forth near Alloa as the vertical image above, taken nearly 50 years earlier. It shows the same area of land and water as the vertical image but is taken with the camera axis pointing to the north-east instead of straight down.

A black and white oblique aerial photo of the same river as in the above image. The same island is visible in the middle, with the town to the left. Fields stretch into the distance. A bridge is visible crossing the river in the foreground.

Features in the background of oblique photographs are often too small to be recognised or are hidden behind buildings. However, they can be very dramatic and more easily recognised by the viewer. During the Second World War these types of images provided information about hard-to-photograph sites such as bunker entrances and caves.

A black and white oblique aerial photo of a beach, taken from very low altitude. The beach is scattered with numerous wooden structures to make landing harder. People run for cover from the reconnaissance plane or dive to the floor in panic.

Ground

Although the vast majority of NCAP’s holdings are aerial photography, it also includes a small amount of imagery taken on the ground. Sometimes these were taken by military personnel for their own interests, while other ground photographs are what are known as camera clearing shots. Before a reconnaissance aircraft departed on a mission, it was good practice to test that the camera was fully functional by taking test photographs. Then on return, any unused film would be exposed. These images occupy the first and last few frames of a roll of film. Aircrew at work, landscape views of the airbase, and nearby aircraft or equipment are often captured in these candid images. Given the secure nature of airbases in times of conflict, photographs of this type are rare examples and an invaluable historical record.

A black and white historic photo of a Spitfire plane seen from the side in a field. It is marked with the letters ‘PL968P’ and an RAF roundel. The cockpit is covered with a tarpaulin. Beyond its static propeller, a second Spitfire is just visible.

More Guides

A greyscale drawing of a plane flying above 6 trees. A triangle pointing straight down from the plane indicates the area covered by a vertical aerial photo. A triangle pointing down at an angle indicates the area covered by an oblique aerial photo.

Types of Aerial Images

The capture of aerial photography has most often been been a systematic process. Learn to identify each type and see how they differ.

A large-scale black and white aerial photo of Glasgow. The river from the previous images now occupies almost the whole frame. At the left side, ships are clearly visible docked next to the river. There are blocks of flats in the bottom left corner.

Scale in Aerial Images

Aerial photographs come in a range of different scales. Learn what impact different scales have on understanding aerial photographs.

A black and white aerial photo of Rosyth docks. The image is busy and confusing. The sea is at the bottom edge with some ships in dry docks or tied up at piers. There are numerous industrial buildings and roads. At centre right is a small woodland.

Interpreting Aerial Images

Learn more about how to analyse and understand aerial imagery to make the best use of it for your research needs.

A blue support for large rolls of film with a black winding handle. A black and white aerial film is being supported on the winder. It is lit from below with a white light.

How to Order Undigitised Images

Not all NCAP collections are digitised and shared on NCAP's Air Photo Finder. Using the historical finding aids or a paid search service, you can request images for scan-on-demand.

An Ordnance Survey map of the Orkney Islands. Islands coloured white are surrounded by a sea represented in blue. The map has been annotated with coloured lines showing where aerial photos were taken.

How to use OS Finding Aids

Finding aids show the geographic coverage of photographic reconnaissance missions in our collection.

A colourful map of a rural part of north Germany (including Wilhelmshaven), with blue representing water and green for woodlands. A straggling line of black boxes marked with numbers from P9 to P50 indicates where a reconnaissance plane took photos.

How to use Second World War Finding Aids

Learn how to use digitised original plotting information, finding aids, from the Second World War. This will allow you to locate and identify historical military aerial imagery of your areas of interest.