Geography Reference
In-Depth Information
You can see in the diagram that the rectangles become longer and narrower. This stretching
also has to be accounted for in the coordinate system. Over long distances, it can cause
rounding and deviations to occur in your data.
If you're dealing with a territory where you only have a defined area of operation, using a
coordinate system more suited to that area is the preferred way of working. As I mentioned
previously, for me here in the U.K. it's often better for me to convert these WGS84
coordinates to OSGB36 before storing them in my database. As we'll see later when we start
looking at spatial SQL, your GIS database can do this on the fly when set up correctly.
That's pretty much all you need to know as a developer. There's much deeper stuff you can
dig into such as spheroid and airy calculations, geodetic measurements, and a lot of that
trigonometry stuff from school. The fact is that your GIS database and many of the tools
you'll use will actually do the vast majority of the heavy lifting for you. So while having a good
knowledge of the actual formulas used by the systems and the Proj.4 strings may be
interesting, I assure you of one thing: it will end up giving you a brain ache.
In the next chapter, we start to move onto more interesting things, starting with the software
we'll be using.
