Comprehensive discussion on types of Photogrammetry and Photographs, Part 1

Here you find a comprehensive discussion over various types of Photogrammetry and various types of photographs. This photogrammetry tutorial is very helpful for understand  the usage of photogrammetry in different sectors.

Metric photogrammetry - It consists of making precise measurements on photographs and other information to determine relative locations of points. This enables to find distance, angle, area, volume, elevation, shape and size of the object.

      The common application of metric photogrammetry is preparation of planimetric and topographical maps. The photograph used for this purpose are mostly aerial photographs, but terrestrial photographs also used sometimes.

Interpretative photogrammetry - This branch deals mainly in recognizing and identifying objects and judging their significance through careful and systematic analysis.

      It includes the branches of Photo Interpretation and Remote Sensing. Photo Interpretation involves in the study of photographic images, while remote sensing involves not only the analysis of photography but also the use of data collected from remote sensing instruments.

Type Of Photographs

In principle, Photogrammetry can be divided as follows:

Depend on lens-setting
 -Far range photogrammetry (with camera distance setting to indefinite), and
-Close range photogrammetry (with camera distance settings to finite values).

Another grouping can be:
-Aerial photography (mostly far range photogrammetry)
-Terrestrial Photography (mostly close range photogrammetry)

Close-range photography:

Close-range photography involves either a hand-held camera or one mounted on a tripod. While aerial photogrammetry is used primarily for terrain mapping, close-range photogrammetry is used to capture images of building facades, vehicles, or any other physical representation that can be seen from ground level.

Close-range (also referred to as terrestrial or ground-based) photogrammetry (CRP) has an object-to-camera distance of less than 300 mt.

Aerial photography:

Aerial photography is 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, and photographs may be taken by a photographer, triggered remotely or triggered automatically. Platforms for aerial photography include fixed-wing aircraft, helicopters, balloons, blimps and dirigibles, rockets, kites, poles and parachutes.

Aerial photography most commonly used by military personnel may be divided into two major types,  the vertical and the oblique. Each type depends upon the attitude of the camera with respect to the earth's surface when the photograph is taken.