Chapter 4

Latitude, Longitude, and Where to get POIs

WHAT’S IN THIS CHAPTER?

  • How to read latitude and longitude coordinates
  • How to convert degrees, minutes, and seconds to decimal
  • Where to get latitude and longitude coordinates
  • Resources to consider for POI harvesting

When you build AR browsers, you must provide geo-coded coordinates to the browser in the format of latitude and longitude (optionally, you can also include altitude). If you’re like me, you were looking out the window during that particular lesson in geography. In this chapter, we’ll have a quick review of how the latitude/longitude coordinate system works. In addition, you’ll also learn of some resources where you can obtain some interesting POIs which you may use later when you build your real browsers. Before we begin, you’ll need a calculator as well as a laptop running a web browser and Google Earth (optional).

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In later chapters, you will use the geo-coded coordinates that you generate here.

An Overview of Latitude/Longitude

You probably have seen latitude/longitude written in either in degrees (using the degrees symbol) or written in decimal. The following examples point to the same location, which happens to be New York City:

  • Degrees, hours, minutes: 40° 43′ 0″ N, 74° 0′ 0″ W
  • Decimal: 40.716667, −74.0

When you build your AR browsers, you must put locations in the decimal format. Since many maps use the ...

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