Module 3 : Photogrammetry
  Lecture  17 : Introduction
 Introduction
  • The photogrammetry has been derived from three Greek words:
    • Photos: means light
    • Gramma: means something drawn or written
    • Metron: means to measure
  • This definition, over the years, has been enhanced to include interpretation as well as measurement with photographs.
Definition
The art, science, and technology of obtaining reliable information about physical objects and the environment through process of recording, measuring, and interpreting photographic images and patterns of recorded radiant electromagnetic energy and phenomenon (American Society of Photogrammetry, Slama).
  • Originally photogrammetry was considered as the science of analysing only photographs.
  • But now it also includes analysis of other records as well, such as radiated acoustical energy patterns and magnetic phenomenon.
Definition of photogrammetry includes two areas:

(1) Metric:

It involves making precise measurements from photos and other information source to determine, in general, relative location of points. Most common application: preparation of plannimetric and topographic maps.

(2) Interpretative:

It involves recognition and identification of objects and judging their significance through careful and systematic analysis. It includes photographic interpretation which is the study of photographic images. It also includes interpretation of images acquired in Remote Sensing using photographic images, MSS, Infrared, TIR, SLAR etc.

Definitions
Aerial Photogrammetry
Photographs of terrain in an area are taken by a precision photogrammetric camera mounted in an aircraft flying over an area.
Terrestrial Photogrammetry
Photographs of terrain in an area are taken from fixed and usually known position or near the ground and with the camera axis horizontal or nearly so.
Photo-interpretation
Aerial/terrestrial photographs are used to evaluate, analyse, and classify and interpret images of objects which can be seen on the photographs.
 
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