- There are two primary methods to obtain precise location in the form of coordinates. 1) survey in the field using traditional surveying techniques or global positioning system instruments, or 2) collect remotely sensed data of the object, rectify the image and then extract the desired coordinate information. Most scientists who choose option 1 now use relatively inexpensive GPS instruments in the field to obtain the desired location of an object. If option 2 is chosen, most aircraft used to collect the remotely sensed data have a GPS receiver. This allows the aircraft to obtain exact latitude/longitude coordinates each time a photo is taken.
Read more about this topic: Aerial Photographic And Satellite Image Interpretation, Elements of Interpretation