Positions are a fundamental element of geographic data. Sets of positions form features, as the letters on this page form words. Positions are produced by acts of measurement, which are susceptible to human, environmental, and instrument errors. Measurement errors cannot be eliminated, but systematic errors can be estimated and compensated for.
This chapter has introduced some of the technologies and techniques used in the acquisition of locational data. You have learned how a variety of location-enabled devices make use of signals from orbiting satellites and how satellite ranging is similar to more traditional surveying methods used on the ground. You have also learned how satellite technologies and surveying instruments can be used in conjunction to correct errors and generate data with higher accuracy.
Now that you know how GPS works, you can start putting it to work. The short list below includes some activities you can do with GPS and the techniques you’ve learned in this chapter:
- Go geocaching! Visit GeoCaching.com or OpenCaching.com to get started.
- Turn on your GPS and create shapes by tracking your path through town: Bostovalentinography
- Do you like to jog? Track, time, and trace your runs: Try MapMyRun.com or TrainingPeaks.com
- Find and catalogue confluences. You’re never farther than 49 miles from a confluence, or location where both latitude and longitude are whole numbers. Go find one! Confluence.org
- Measure your yard, record your favorite fishing spot, or enhance your golf game by knowing just how far the pin is. The possibilities are endless.