GIS and Remote Sensing

7. GPS & Photogrammetry

The Global Positioning System is known as Navstar GPS or simply Navstar is a global navigation satellite system (GNSS) that delivers geolocation and time information to a GPS receiver in all climate and weather conditions, anywhere on or near the Earth where there is an unhindered line of sight to four or more GPS satellites. The GPS system operates independently of any telephonic or internet reception, though these technologies can improve the usefulness of the GPS positioning information. The GPS system provides critical positioning capabilities to military, civil, and commercial users across the world.

Photogrammetry is the science of making measurements from photographs, particularly for recovering the exact positions of surface points. It may also be used to recover the motion pathways of selected reference points on any moving object, on its components, and in the immediately adjacent environment. Photogrammetric analysis may be applied to one photograph, or may use high-speed photography and remote sensing to detect, measure and record complex 2-D and 3-D motion fields (sonar, radar, lidar, etc.). Photogrammetry feeds dimensions from remote sensing and the results of imagery analysis into computational models in an attempt to successively estimate, with increasing accuracy, the actual, 3-D relative motions within the researched field.