Before describing the operation of the V-STARS system, a brief introduction to photogrammetry software is provided for those who are unfamiliar with the technology. Photogrammetry, as its name implies, is a 3-dimensional photogrammetric coordinate measuring technique that uses photographs as the fundamental medium for metrology (or measurement).
The fundamental principle used by photogrammetry is aerial triangulation. By taking photographs from at least two different locations, so-called "lines of sight" can be developed from each camera to points on the object. These lines of sight (sometimes called rays owing to their optical nature) are mathematically intersected to produce the 3-dimensional photogrammetric coordinates of the points of interest. Aerial Triangulation is also the principle used by theodolites for coordinate measurement. If you are familiar with these instruments, you will find many similarities (and some differences) between photogrammetry and theodolites. Even closer to home, triangulation is also the way your two eyes work together to gauge distance (called depth perception).
This primer is separated into two parts. Photography describes the photogrammetric principles involved in photogrammetry, while Metrology describes the techniques for producing 3-dimensional coordinates from two-dimensional photographs.
Aerial Photography -The First Part of Photogrammetry
Taking photographs is, of course, essential for making a photogrammetric measurement. To obtain the high accuracy, reliability and automation the photogrammetry system is capable of, photographs must be of the highest quality. Fortunately, because of the design of the system, photography with V-STARS is actually simpler than film photography.
Posts
