Digital survey
Introduction
Photogrammetry is a set of techniques that, using a photographic camera, allow deducing a conical projection of the image, its dimensions and the location of an area.
Its etymological roots come from Greek, and are: φος, φοτός: nominative and genitive of light, γράμμαρ: graph or writing, and μετρία: measurement.
Photogrammetry classification
According to the methods used:.
According to the measurement used:.
Advantages and disadvantages
Thanks to the advances in computer science and computing techniques (with their respective technologies), digital photogrammetry is the most used currently. It allows all photogrammetric processes to be carried out with a computer, which simplifies the entire process.
Advantages:.
Disadvantages:
Basics
Contenido
Para entender el proceso de la fotogrametría digital primero se han de explicar algunos conceptos básicos.
Support point
A fulcrum is a point of known XYZ, XY, or Z coordinates that is used to make an external orientation. The (PA) were formerly obtained with theodolites through a process called polygonal; Today they are obtained with GPS. The support points are usually 6 or more.
checkpoint
The control point (PC) is a point with known XYZ, XY or Z coordinates that is used to do an error control of the generated stereoscopic model.
Internal orientation
Internal orientation consists of the reconstruction of ray beams with characteristics homologous to those prevailing in the photographic camera that originated these images. In other words, through internal orientation the aim is to reconstruct the ray beams.