Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring, and interpreting photographic images. It involves the use of photographs (often taken from the air or ground) to create maps, 3D models, and other representations of objects or spaces.
Photogrammetry has evolved from simple photo interpretation to advanced techniques involving digital images and software algorithms. There are two primary methods of photogrammetry:
Stereoscopic Photogrammetry
Stereoscopic Photogrammetry or Stereoimage Interpretation involves capturing two or more images of the same object or area from different angles. By analysing these images simultaneously, usually with the aid of stereoscopes, a 3D model or map of the area can be created. This technique leverages the principle of stereopsis (the perception of depth) and is widely used in topographic mapping, architecture, and archaeology.
Structure from Motion (SfM):
Structure from Motion is a more modern approach that uses multiple overlapping images taken from different viewpoints. Unlike traditional stereoscopic methods, SfM does not require precise camera positions or angles. The images are processed using computer algorithms to automatically identify and match features across images, allowing the generation of 3D models and point clouds. This method is particularly popular in digital photogrammetry for creating detailed 3D reconstructions of landscapes, objects, and buildings.