Photogrammetry is a technique used to obtain accurate three-dimensional measurements of objects and environments through the analysis of photographs or imagery. It involves extracting information about the shape, size, and spatial properties of physical objects or scenes from photographs taken from different viewpoints. The word "photogrammetry" is derived from the Greek words "photos" (light) and "gramma" (drawing or measurement).
The process of photogrammetry typically involves the following steps:
Image acquisition: Multiple photographs of the target object or scene are captured from different angles and positions. These photographs should overlap to provide sufficient data for reconstruction.
Image processing: The acquired images are processed using specialized software to identify common features or points that appear in multiple images. These points serve as reference markers for the reconstruction process.
Triangulation: The software uses geometric principles, such as triangulation, to determine the three-dimensional coordinates of the identified points. Triangulation involves measuring the angles formed by the lines of sight from the camera positions to the common points in the images.
Point cloud generation: The triangulated points are then used to create a point cloud, which is a set of 3D coordinates representing the surface of the object or scene. The point cloud provides a digital representation of the geometry.
Surface reconstruction: The point cloud is often further processed to generate a continuous surface, creating a 3D model of the object or environment.
Photogrammetry is widely used in various fields, including surveying, mapping, architecture, geology, forestry, archaeology, and computer graphics. It provides a non-contact and efficient method for creating accurate 3D models of physical spaces or objects, and its applications continue to expand with advancements in imaging technology and software.