Why Use Photogrammetry?
Photogrammetry allows for the extraction of three-dimensional features from remotely sensed data (close-range, aerial, orbital, etc.). Applying photogrammetric techniques is not a trivial process and the learning curve can be near vertical (no pun intended). In fact, when dealing with aerial photography or satellite imagery, there are alternative methods for geometrically “adjusting” spatial data that are relatively simple (e.g. rubber sheeting). Although these methods do play an important role for GIS users, they do not create a suitable product for making accurate geometric measurements. The photogrammetric process is needed to confront the inevitable systematic and non-systematic errors introduced when an image is captured or made digital (e.g. terrain relief, camera orientation, lens/sensor distortion, and scanner distortion). It is only after solutions are found for these errors that accurate topographic and plainimetric information can be extracted from a digital image.
