This week we're going to look at how to choose a coordinate system for your database. In PostGIS, this includes the choice of geometry vs geography columns, as well as which projection (if any) to use, and how to interact with it from Rails.

Scaling, scaling, scaling. Can Rails really scale? It's been a source of FUD and the butt of running jokes. But scaling is a serious matter when it comes to large data sets, and it's something we need to pay attention to in the geospatial realm where big data is commonplace.

The location revolution is a revolution of data. Ubiquitous data, from mobile GPS and user input as well as from census and other datasets, is what makes location-aware applications possible. And so the first task of many geospatial projects is to determine how to find and utilize (and, in some cases, produce) external data.

When people speak of a learning curve in geospatial programming, they're usually referring to handling coordinate systems. It's true that many spatial applications require close attention to the coordinate system, and it's true that there are some difficult concepts involved. However, it's been my experience that once the light bulb turns on, it opens up a lot of the power and potential of geodata.

RGeo is a library and framework for handling spatial data in a Ruby application. It's currently designed more for completeness than ease of use, so there's a bit of an initial learning curve. This article is an attempt to smooth that learning curve a bit. It contains a tutorial introduction to RGeo, covering the basics that every RGeo user needs to know, and a bit of discussion of where the library came from.

Before going in depth into any particular topic, I thought it would be useful to write a getting-started tutorial, walking through setting up and working with a simple example Rails app using RGeo.

It was about a year ago that I released the first public version of RGeo, a geospatial framework for Rails and Ruby applications, along with a bunch of add-on libraries and ActiveRecord adapters designed to work with it.

RGeo has enjoyed some success so far. But over the past year, I've fielded a number of questions from folks struggling with it, and I've come to realize that it is not very easy to learn or use. A lot of that is my fault. The core RGeo framework is fairly complex, and neither RGeo itself nor its add-on libraries are particularly well documented. Furthermore, geospatial technology is not an easy topic in general. A number of concepts and a fair amount of math has to be understood before you can really get off the ground with a location-aware application beyond the most simple display of a few pushpins on a Google map.

My hope is to start changing that.