When dealing with LBSs it is first important to be clear about the meaning of the term “location”. Although most people would claim that they are very familiar with the concept of location, as it, besides time, is one of the major quantities determining our everyday life, it is useful to have a closer look at it and to distinguish between different categories of location information. This chapter provides an overview of these categories. The main focus is on one spatial location that appears to the developers and users of LBSs in the form of coordinates. This chapter introduces the different ways to express a spatial location in a coordinate system and explains the idea behind datums, which are used for modeling the surface of the Earth. Furthermore, an introduction to the fundamentals of map projections is given, which are needed for projecting the bended surface of the Earth on a planar map.

Contents

• Location Categories
• Spatial Location
  • Coordinate Systems
  • Datums
  • Map Projections
• Conclusion