Chapter 9. Real-Time Data

A common saying among geospatial analysts is, A map is outdated as soon as it's created. This saying reflects the fact that the Earth and everything on it is constantly changing. For most of the history of geospatial analysis and through most of this book, geospatial products are relatively static. Raw datasets are typically updated from a few months to a few years. Data currency has traditionally not been the primary focus because of the time and expense needed to collect data.

Web mapping, wireless cellular modems, and low-cost GPS antennae have changed this focus. It is now logistically feasible and even quite affordable to monitor a rapidly changing object or system and broadcast these changes to millions of people online. This change is revolutionizing geospatial technology and taking it in new directions. The most direct evidence of this revolution is web mapping mash-ups using systems such as Google Maps or OpenLayers and web accessible data formats.

The term...